#and he'd most certainly play along if he was aware of the assumption

[daisybell-on-a-carousel]

It had started because some people had misheard something Phantom said. One singular letter was responsible for the mess he was in right now.

They thought Phantom had said "Dad"

He had not, not this time at least, he was, admittedly, rather prone to accidentally calling Jack "Dad" because the man actually was. Though those moments were nothing compared to this.

It had spread like wildfire throughout the school, and then the city as a whole. Phantom had a dad, a dad who was visiting next week. That's what they knew, and theories and questions were already abound. Was Phantom's dad alive? Or dead too? What was their relationship like? Was this mysterious dad Phantom's blood (ectoplasm?) father? Or was Phantom adopted? How similar were they?

Dan just laughed at Danny over the phone when he tried explaining the situation to his older self before he came by to visit.

[artytaeh]

⋯ ⋯ ﹒ 🪻 ’

MATTHEO RIDDLE— not horribly tall, but slightly above average. strong arms; what he doesn't have of height like the weasley twins, he has of muscles on his arms, even though not a ken-like amount, which he finds ugly. dark curls— inherited by his mother, the insanely crazy bellatrix lestrange, and beautiful eyes that he has no clue where he got from. long lashes, defined jawline.

in short, a handsome, easily found attractive, young man. and with that bad boy attitude? well, mattheo riddle is every girl's guilty pleasure of a daydream.

some, because they'd like to have their attitude and confidence fucked out of them, by mattheo riddle who certainly takes no bullshit. others, because they delusionally believe that they can somehow fix him— turning a doberman into a golden retriever.

mattheo riddle who's the only first year to not tremble under snape's gaze, because his father is voldemort. the thing, the person he fears the most.

mattheo riddle who doesn't even blink when teachers, older students and even intimidating people yell at him— this is child's play, compared to the cold, frightening aura of his father, and the eery sound of his mother talking to him; one second, she's calm, putting on a (scary) loving persona— then, she's raging, yelling and slamming things, hands on the table, almost throwing hands at her son.

mattheo riddle who stands on the end of the line, letting students get in front of him and even threatening some to take his place on the line, so he stands further behind. this only happens once, during that one professor lupin's class, with the boggart— because mattheo knows that it'd take the shape of his father, walking eerily towards him. not only does he hate the thought of having his classmates gossiping about him, about his family and making even more assumptions about him; but also knows that he'd stand there, paralyzed. incapable of even raising his wand, much less utter such an easy spell like riddikulus. for mattheo, what's ridiculous is his situation; how he'd love and thank the heavens, if he could have such a silly fear like insects, ghosts, or even clowns.

mattheo riddle who grows extremely confident because nothing scares him at hogwarts; after all, his father isn't there— the only thing that makes mattheo riddle tremble is his presence. anything else isn't half as frightening as coming back home to his mother, bellatrix lestrange, and father, voldemort he-who-must-not-be-named.

mattheo riddle who becomes scary and intimidating, so that no one can scare or intimidate him instead. he spent most of his third year at hogwarts practicing on the mirror— a way to turn his beautiful eyes into a dead stare, making sure that the shining glint of his eyes disappears, to become so scary, that no one would dare to mess with him like tom riddle does. or even draco malfoy, who tried to do this back on their first year, bullying mattheo into becoming his friend and follower—, but all of this was before they became genuine friends, along with theodore, lorenzo and blaise.

mattheo riddle who's known by the unhinged brother, less smart riddle— while others, who are aware of tom riddle's tendencies, call him the older psychopath brother, brilliant riddle. such a charming pair of siblings, aren't they?

mattheo riddle who smokes a whole package of cigarettes with theodore nott, when they're on the train back home. for holidays and for summer vacation, in silence, because they're too anxious and nervous to come back home, to leave their (although they're too proud to admit) safe place — hogwarts.

mattheo riddle who respects his older brother, tom riddle, because he thinks that in many ways, tom is like their father sometimes. and that scares him.

mattheo riddle who only learned how to swim and to stop fearing lakes, when his slytherin friends teached him.

( this happened on lorenzo's house, since he invited his friends to spend some days there, during summer vacation. after all, his parents are the less... frightening, in a way, and blaise zabini gatekeeps his mother from his friends, for obvious reasons. besides, lorenzo has the largest pool! upon realizing that mattheo stayed behind while they played in the swimming pool, the boys, for once, didn't turn the situation into a joke. draco stood behind, throwing opinions and dictating that they were doing it wrong— while theodore and blaise stood each by mattheo's side, making sure that he wouldn't get scared if he felt like he was drowning, while lorenzo is in front of him, advising on what to do. it was a mess. a mess that became a core memory of true friendship. )

even so, mattheo hates to go to a point of the lake where he's no longer tall enough to touch the sandy surface— because suddenly he's seven years old again, with tom riddle standing on the edge of the lake, smiling darkly at the sight of his baby brother drowning in the cold water.

⋯ ⋯ ﹒ 🪻 ’

mattheo riddle who, after all of these years, still stares at his older brother with a mixture of resentment and sorrow— secretly, mattheo still wishes to be close with tom. to have a normal brotherly friendship with him, even if they're everything but a normal family. so, mattheo riddle, who envies pairs of siblings whenever he sees them around hogwarts halls, hugging, lightheartedly bullying each other. wishing he could trauma dump shared experiences of his parents with tom, who would've demolished inch after inch of mattheo's pride and feelings, calling him weak.

mattheo riddle who doesn't join draco when he bullies the weasleys. he never defends them either; he doesn't need to, because the redhead siblings stick around for each other. mattheo doesn't know if his heart feels like crying, or ripping apart with a vicious, angry jealousy that he doesn't have that. a sibling that cares enough to take care of him.

mattheo riddle who drinks and drinks and drinks until he passes out, or until he almost throws up his stomach away— rarely accepting any kind of help whatsoever, because he doesn't feel like he deserves it.

because pain and finding out a way to solve things by himself, is what he grew up used to. because his mother is a bipolar, sadistic woman; because his father is too feared by mattheo for him to even dare to consider asking for his help; because his older brother, tom riddle, isn't a pillar he can lean on to— rather, a pillar that would glady fall on top of him, crushing him under debris. he's another person to be feared, and who'd leave mattheo even worse than he already is.

mattheo riddle, who hesitantly accepts lorenzo and theodore's help. because lorenzo is too much of a mother of the group (whenever blaise isn't around, but mattheo doesn't think he'd ever allow the zabini boy to help him either. of course, this happens whenever lorenzo isn't planning his way to another girl's bed either) and by far, the most caring of the boys. or at least, the one who easily shows his worry without a hundred walls surrounding his heart.

and theodore nott, well— mattheo thinks that the term best friend is too corny, so he settles to admit that theo is the person who understands him the most. if he doesn't have tom, he has theo, to sympathize with his shitty situation, because theo's family and hardships are too similar, even though they don't share a last name.

they have matching wounds, inflicted by different people, but similar situations.

and because theodore is awfully moody, sarcastic and would punch mattheo into reason, well— mattheo unwillingly accepts theodore's (forceful) help.

· · ·

mattheo riddle who only ever has deep thoughts when he's throwing up from the alcohol, or becomes self-conscious of himself. of the evilness he provokes, of the unchanging way his fate was decided, as soon as he was conceived in his mother's womb. how he, no matter how he'd like to change, believes that he's a lost cause.

something that's not worth the effort, since mattheo riddle, younger brother of tom riddle, son of bellatrix lestrange and the dark lord himself, must have been born with a vicious evil heart. how could he not, with a family like this?

it must be on his dna. or so he believes.

when he's drunk, puke being wiped out from his lips and alone in the bathroom— this is the only time when mattheo riddle allows himself to pity himself. other than that, he'd scoff at the thought of doing so; because that's a weak thing to do.

and to survive his family, mattheo wouldn't dare to be weak a single day of his life. he might get killed if he allows a moment of weakness around his family. whatever family means, anyways.

⋯ ⋯ ﹒ 🪻 ’

mattheo riddle who's always the first one to start a fight— and never the one to end it. either his friends push him away, or he's held down by some spell casted by one of hogwarts' teachers.

however, he will start a fight with a group of five gryffindors, if they make a nasty comment about mattheo's friends. if they dare to assume, to gossip, to say one mean word about the friends that tolerate mattheo's behavior even on his shittiest days. the first thing he does is grab the last one talking by the collar, so that his fist naturally punches the guy's face. yes, mattheo can keep up a fight with five guys— even though he knows that, as much of a good and violent fighter as he is, there's no way that he won't leave with a few bruises (and bloody knuckles from rashly punching back and forth).

nevertheless, mattheo riddle won't ever allow theodore or his friends to join him, if he's about to have a 1v1. not even to intimidate or make a single threat— mattheo thinks that it's pathetic and coward to do so, which is why sometimes, mattheo doesn't help draco when he puts up a stunt against a single student (or a group that is outnumbered by malfoy's little friends). when draco comes back, mattheo won't scold him— but he won't shut up either, at least making sure that by some miracle, draco understands how coward it is to do that, from the sarcastic comment that mattheo throws with no hesitation.

⋯ ⋯ ﹒ 🪻 ’

mattheo riddle who actually has one of the most beautiful smiles. once his usual dead stare is gone, showing how those dark eyes of his can look so sweet and bright— squinting into half moons, when he truly laughs or smiles genuinely. his smile is one that makes you think that maybe, just maybe, there isn't any evil or meanness to this slytherin boy.

mattheo riddle who is so touch starved, that only a warm gaze from you, is enough to melt him and (at least mentally) get him on his knees. those dark eyes soften and follow every movement of yours— looking like a lost puppy, when you eventually shift your attention to something else, your gaze leaving him. he won't grab you, he won't yell for your attention out of pride— but if you were to look into his eyes, you'd see how mattheo silently hopes to some deity that you'll have your attention on him once again.

mattheo riddle who doesn't know how to be gentle, because he never knew gentle touches, caresses and soft approaches. this man is almost stupid because of this sometimes— mattheo isn't even aware of his own strength, so when he does hurt you unintentionally (by grabbing holding your wrist) and gets scolded about it... he'll genuinely look at you, confused. sure, he'll apologize— fine, sorry!

. . . however, mattheo isn't sure what he did wrong. was it really that hurtful? to him, he was simply holding you, not grabbing...

( because mattheo riddle was never held, only yanked or dragged along. )

mattheo riddle who would love to have people playing with his hair. twirl his curls around your fingers, tug at it (but gently, please! he easily complains at the slightest hint of discomfort!), massage his scalp, caress his dark hair— mattheo melts and for a moment, wonders if sleep does arrive to him this fast at night, like it does now that you're touching him there.

so yes, during classes, mattheo sneakily stands on the door frame— carefully watching where you decide to take your seat, before he marches up to you so he can take the other chair of said desk.

mattheo marches confidently, hands on his pockets and body a little bend to the front; focused on his target: you.

all of his concentration is locked on his goal: your attention for the whole class. and if he's too late, because some annoying girl or asshole with pants got there before him? one glare from mattheo, and they're gone.

mattheo doesn't even bother to take his books; he greets, crosses his arms on top of the table, settles his head there— and if you're too slow to understand what's this whole preparation for, well, mattheo has no problem to make his intentions clear, by (much gentler, this time) grabbing your hand and settling it on his head. among his dark curls.

and if you notice that they look softer and taken care of— well, mattheo won't be catch dead and much less alive saying it. but blaise noticed how mattheo bought a new shampoo, conditioner and a weird bottle that seems to help curly hair like mattheo's.

AND HOW DID AN ALL-IN-ONE SHAMPOO USER LIKE MATTTHEO, KNEW WHAT PRODUCTS TO USE IN WHICH ORDER, FROM DAY TO NIGHT? oh, that was easy; mattheo spent an evening leaning against the entrance of the slytherin common room, watching intently every student that entered or left during that hour of the day. his eyes glared up and down— searching for a slytherin, be it a witch or a wizard, older or younger than him, that has a type of hair similar (if not identical) to his.

finally, a slytherin girl was on her way to hang out with her friends. that is, until mattheo nonchalantly grabs her by the collar of her shirt, right when she innocently passes by him, then drags the girl along with him to a secluded corner of the slytherin common room.

( out of love for life and respect for their well-being, it's safe to say that her friends didn't come to save her. though, props to them, because they kept watching... just in case. of, you know, having to search for help. )

the slytherin girl trembles on her spot, rethinking her life choices; wondering if she had done anything to offend mattheo riddle, the dark lord's son— not the psychopath, the unhinged one. when he bends down, so that he's face to face with her, eyes squinting with his jaw clenched...

she closes her eyes. wondering if she'd be punched or have her hair grabbed to be slammed against the wall. however, after awkward ten seconds pass and her body is still intact, she opens one eye, to see mattheo making a grimace.

a grimace that would be funny if he wasn't so scary. a grimace that seemed to ask, 'what the fuck are you doing?'. which would have been verbalized, mind you, if mattheo didn't have a list of priorities at the moment. he opens his mouth, and this slytherin girl feared to have hallucinated such an innocent, random question.

'which products do you use for your hair?'

( ten minutes later, after having explained her hair routine in detail to mattheo riddle himself, who took notes and hummed for her to keep going, the slytherin girl goes back to her friend group. pale. she doesn't give details— no one would believe her. and she doesn't think that mattheo riddle would like having people know that he's about to spend 100 galleons on hair products to please you. )

౨ৎ please understand that i'm trying my hardest, ♡ ͡

my head's a mess, but i'm trying regardless . . .

🪻 ; . . . fandom : harry potter.

— i noticed that i have a few mattheo girlies enjoying my writing, so! please consider this a little bittersweet drabble for you. once again, tysm for the feedback! ♥︎

the headers + gifs + icons aren't mine. credits to the respective creators ! 🌷

[a-master-procrastinator]

Long ass post about the Eternal family not being a copy-paste from ATLA (aka I like the memes but my god can you please stop)

Because some people truly think that Vaylin is off-brand Azula, Arcann is Zuko and so on.

It's. Called. A. Trope. (I mean how often do we come across abusive manipulative fathers in media? Mothers who couldn't much to change anything? Children, desperately looking for their parent's approval no matter what?)

Of course, you have to consider the fact that the writing of ATLA is simply better than of KotFE/ET, so this might have been one of the reasons why people say that.

Spoilers for Avatar: The Last Airbender, Knights of the Fallen Empire and Knights of the Eternal Throne expansions!

Okay, so here's my unprofessional, maybe biased, not super deep take.

(not going to mention that all of them are members of royal, ruling family, kinda obvious)

What roles do they play in their stories? Well, both Valkorion and Ozai are main antagonists, but their presence throughout the story is very different. Ozai is rarely shown in first two seasons, we don't even see his face until season 3. He doesn't have a direct connection to the protagonist, they only meet at the very end of the show, and Ozai's role is to pose a threat to the world, while Aang's is to save it. Valkorion, on the other hand, is constantly on the screen, interacting with the main character, challenging their viewpoint and influencing them directly. His end goal is similar to Ozai's (destroy everything and be the only ruler of the his nation), but with one major difference - he's trapped in Outlander's mind, so to achieve his goal Valkorion attempts to take control of the main character. Their interactions play important role in the story, and we spend a lot of time with Valkorion.

In addition to that, their relationship with children are also not exactly the same. It seems like Azula is Ozai's favorite and Zuko is a failure in his eyes until he meets his expectations, and the same goes with Vaylin, Arcann and Valkorion, right? Well, partially. Indeed, Valkorion and Ozai's treat their sons in similar ways (are disappointed in them until they meet their expectation by doing something that goes against their morals), but when it comes to Vaylin and Azula, it's not that easy. See, Valkorion claims that Vaylin was always his favorite creation (even though we know it's actually his empire), and he certainly seems to take pride in her potential in the Force. But her power is the very reason he's afraid of his own daughter, and in this fear Valkorion literally locks Vaylin away and allows to put her through physical and mental torture just to make sure she won't become a threat, won't overpower him. Maybe he thought of her better than of Arcann, but she wasn't his favored child for sure. I don't want to say that Azula hasn't experienced abuse from Ozai, but for the most part he clearly favored her over Zuko. He has never shown fear of Azula's power and abilities (or at least I haven't noticed), quite the opposite - allowed her to do a lot, as long as she brings results.

I could also mention their slightly different characterization (mostly that we get more characterization of Valkorion, get to learn his motivations, views, philosophy and all that, also he's portrayed as more nuanced, even if he not really is) and role in their respective governments (ozai is one of many Fire Lords and arguably not the greatest, while Valkorion is a god to citizens of Zakuul, their only Immortal Emperor), but those are details, and I think you get the point.

What's similar: role of the main antagonist, manipulative and abusive father, goal of destruction of everything that isn't their nation/empire, relationship with disgraced son.

What's different: presence in the overall narrative, relationship with the main character, relationship with daughter, role in their societies.

Senya and Ursa are even less similar. Yes, they both are mothers who love their children, but have to leave them, but these are probably the only things they have in common. Just as with Ozai and Valkorion's presence throughout the story, Ursa is only shown in flashbacks (for obvious reasons), and Senya is one of major characters in KotFE and (a bit less major) in KotET. Ursa leaves because she has to kill Azulon in order to save Zuko, and later isn't present in the story (I'm aware that her fate is told in comics, but we aren't talking about it). Senya leaves because when she tries to take children with her, they refuse, and she understands that she can't force them to, nor she can help them to break free from Valkorion's manipulations. For a long time she's absent from Arcann ad Vaylin's lives, but at the time of game events she attempts to save her children and stop the madness and destruction they've caused, and it isn't a small part of the story.

I also want to add that their relationship with Ozai and Valkorion are also different, but can't say much about Ursa. I heard that she didn't choose this marriage and suffered emotional (and maybe physical???) abuse from Ozai. I can say with confidence, though, that Senya genuinely loved Valkorion, and strangely enough, he seems to at very least respect her. But, of course, this wasn't the best marriage either.

Plus, we see more of Senya's relationship with Vaylin than Arcann or Thexan, but with Ursa we see her more with Zuko than Azula. Just a detail to remember.

(also Senya is simply a better character but that besides the point, moving on. in this house we stand Senya)

What's similar: role of loving and caring mother, abandoning their family at some point.

What's different: presence in the overall narrative, relationship with husband, characterization in general.

Boy, where do I even begin. Vaylin and Azula are similar in that they are both extremely powerful (one is firebending prodigy, the other is potentially stronger than Valkorion), both are cruel "craaaaazy" (i hate that cliché), both are younger sisters, have serious mother issues (seemingly more so than father issues), both go through betrayal of people they could always rely on, which eventually leads to their downfall. But when I took a look at their personal arcs, it became clear that they aren't the same (unfortunately, Vaylin's arc is very rushed and underdeveloped, but we'll have to go with what we have and my personal view, sorry).

There's a really good video about writing corruption and madness, and I'm going to base my thoughts on it. To summarise it: a good corruption arc should have 4 components:

- the character has a specific goal (or a goal and subgoals);

- in pursuit of said goal they become the cause of a significant event that brings serious consequences;

- as the result of these consequences, character abandons their morals, ideals or a code in pursuit of goal;

- character either will not achieve their goal or will succeed, but it won't be enough to satisfy them.

And then the author brings Azula's arc as one of the best examples of compelling story of corruption (so basically, she represents it perfectly). In short, Azula's main goals are perfection and control, and subgoals help achieve the main ones. In pursuit of these goals, Azula causes Mai and Ty Lee to betray her (by pushing them too far to do something they wouldn't do), which then causes her to become paranoid, which makes her to attempt controlling everything and everyone around her, *breathes* which makes her lose control over herself and ....

Now, I thought if Vaylin's arc could fit into a corruption one, and next part will be based a lot on my assumptions and personal view of her character (plus rushed writing doesn't help), but I think yes (or at least mostly). The difference is in goals, ideals and details.

While the story strongly makes us think that Vaylin's goal is freedom (or control over her life and everything around her) or power and destruction, I think it's actually self-determination (which was said by Tenebrae in 6.2) and feeling safe. Let me explain (and here I thought this would be a short comparison). Sure, when Valkorion caged Vaylin on Nathema, he took choices and control over her life from his daughter. But let's not forget whom Vaylin blames for this (even more than Valkorion): her own mother, and I think this details tell us that the most important thing that Vaylin lost on Nathema is feeling safe. Then, after Arcann brought her home, I assume Vaylin still didn't feel safe enough under Valkorion's rule, still too afraid that he'd simply send her back to that hellish place.

It's when Valkorion is struck down Vaylin finally has a feeling of personal safety, even if she isn't the one on the throne. Why? Because back on Nathema there were two people who haven't turned on her - Arcann and Thexan (yes, this is also a huge assumption, bc the game states that only Thexan visited her, but it doesn't make much sense).

I've always noticed (and I'm not alone in this) that her behavior in Fallen Empire is different from the way she acted in Eternal Throne. Most likely bc of rushed writing, but I see a character driven reason here. In first of these expansions, Vaylin is the second person in power on Zakuul, and with Arcann being in charge, person she can trust more than any other living being, she feels safe - she can test her power, and now Valkorion won't prevent it, she can do pretty much everything she wishes, and the most Arcann will do about this is mildly complain (without blaming her). Really would be nice if we got to see any normal hobbies of Vaylin (like wasn't there something about books or art?), but I digress. She might have some questions about Arcann's tactics, but they get along just fine. The important thing to note is Vaylin not seeking to hunt the Outlander personally, to rule or conquer the rest of the galaxy, or trying to achieve absolute freedom or power. She's kinda there.

This, however, changes when Arcann doesn't allow Vaylin to kill Senya. Their relationship was getting somewhat worse towards the end of KotFE, but this is a turning event Vaylin caused by attempting to strike her mother. By saving the person Vaylin blames for all the trauma from sending her to Nathema, Arcann threatened her feeling of safety. And now Vaylin starts to believing that to achieve safety she now needs to kill people who hurt her (that's why she's so determined to find Senya and Arcann), take the throne and hunt down Outlander (she was manipulated by SCORPIO to these subgoals).

(The following is the weakest, I'll admit, but I hope I can at least express what I see). So, in trying to achieve goals she didn't want before Vaylin loses in self-determination, being either driven by overwhelming anger or manipulated by others (SCORPIO or Commander on Odessen), desperately trying to accomplish anything, or even goes against her morals (like by erasing GEMINI's free will protocols, when earlier she agreed that freedom to choose is important; or breaking the deal on Odessen). All of these result in her downfall.

But even this isn't the end. The key difference between arcs of Azula Vaylin lies in it's resolution, or that Vaylin have a chance to overcome corruption in the main narrative (and Azula doesn't. again, not including comics here, sorry). After death, Vaylin is again controlled by Valkorion in Outlander's mind. First time physically (she can't resist it), second time mentally. This is where Vaylin has to choose - kill brother who betrayed her and Commander who killed her, or go against Valkorion, person responsible for almost all of her pain and trauma. She has t choose by herself, and I think it's a good start.

Now, before 6.2 we all thought Vaylin was dead for good, but that story update hinted at possibility of her coming back to life. What I like to think is that now that she dealt with people responsible for her trauma (helped defeat Valkorion and actually for once listened to Senya), Vaylin can now have a different life, finding herself with support of someone she doesn't hold a grudge against and who treats her well (Satele, I mean).

I'm so sorry for going into details, but I needed this long explanation to present the point (and I suck at explanations). As said before, this is my version of her arc, and most likely wrong interpretation, but even with personal freedom of choice, Vaylin character differs from Azula a lot.

Need I mention that Vaylin relationship with Arcann and Valkorion are drastically different from those between Azula, Zuko and Ozai?

(Also a little detail - with royal family of Fire Nation, Azula is the golden child, while with Tiralls it's actually Thexan, not Vaylin).

What's similar: role of extremely powerful, emotionally damaged daughter with little to no regard towards others, close people betraying them, resulting in their downfall.

What's different: characterization, role in the narrative, relationship with father and brother.

Arcann and Zuko is the most difficult part, but I still believe that calling Arcann just a cheap copy of Zuko is incorrect.

So, they fall into role of less successful son, always getting disapproval from father, being in shadow of more talented sibling, both obsessed with capturing the main character but ending up helping them end the war after going through a redemption arc with help of caring family member. Even both have scars on left side of face. Yeah, seems similar. I still think they are different characters.

Let's start with their relationships with family. In Valkorion section I said that his attitude towards Arcann is similar to that of Ozai towards Zuko, so not going to spend too much time here. However, there's slight difference - Zuko didn't kill his father even he had a perfect opportunity (bc it wasn't his goal), Arcann did (bc it was one of his goals), which says something about their characterizations.

Zuko and Ursa were shown to have a good mother-son relationship, and it played a role in Zuko's character. With Arcann and Senya, we don't really know (not much was shown in expansions). We know Arcann didn't hate his mother, but possibly didn't have warm memories of her either. The reason is most likely, like Senya said, her children wanted nothing to do with her (which is a bit untrue about Vaylin, but okay) and leaned more towards Valkorion. We need to remember that on Zakuul Valkorion isn't just one of many great leaders, he's the greatest, and seen as a god by most citizens, so safe to assume the same would apply to his children as well.

Zuko and Azula's siblingship (i'm out of words) is a bit similar to Arcann and Vaylin's in way of brother knowing that his sister isn't good, but still caring about them (even if not showing). At least it's what I saw. What's different is how Azula treats Zuko, compared to how Vaylin treats Arcann. I think Azula showed compassion or concern for Zuko maybe twice, but I'm not entirely convinced that it was 100% sincere. Vaylin, on the other hand, seems to trust and care about Arcann (with bits of sass and questioning his life choices), and switching to complete opposite after him saving Senya. Also, I don't she ever called Arcann a failure in their father's eyes.

Now I want to say that their roles in stories aren't the same either. Sure, both are introduced to us as antagonists, but in reality, Zuko was never a true antagonist (we get to learn this somewhere mid-season 1), when Arcann remains the main antagonist for whole of KotFE. Zuko didn't start a war and didn't participate in conquest of other nations too much, his main goal was to capture the Avatar so to restore his honor (and deserve his father's forgiveness). Honestly, I think it's safe to say the Zuko is one of two main protagonists of ATLA. Why does Arcann want to capture the Outlander? Solely because his father's spirit still lives inside this person's mind, and the best solution to keep Valkorion away from the galaxy is not letting the Outlander free (hence the carbonite freezing). And Arcann doesn't want or need Valkorion's forgiveness when he attempts to kill him (or kills him, depending on your choice. anyway, his action directly leads to Valkorion's "death"). And right after that he becomes a ruler of Zakuul and begins the conquest of Republic, Sith Empire and everything he can reach (the reasoning behind this is still unclear to me though; maybe because he was raised with ruling Zakuul in mind and he didn't anything else, idk). Point is, he's responsible for war and main's character imprisonment, which makes him the main antagonist of KotFE. They have it the opposite ways - Zuko starts as disgraced prince, supported by a little group of people, and in the end he's recognized and appreciated by his nation, and Arcann starts as respected by his empire, later becoming less and less loved, until some groups start rebelling his rule, and in the end he doesn't get to rule Zakuul again.

This leads me to their morals. See, Zuko didn't have the worst morals in Fire Nation, even more, he expressed care for loyals soldiers of his nation before getting punished by Ozai. During first season (and about a half of second one) his views on other nations are what he was taught before. However, these views are challenged by travelling in Earth Kingdom, witnessing people suffering from war Fire Nation started and hating its people (you already know all of this), and with this he comes through final stage of redemption when he's back home. Unfortunately, Arcann doesn't go through this, and he's shown to be more ruthless.

Alright, when it comes to their redemption arcs, well let's say they are different (both in quality and the way they go through it), I'm just a bit tired of long explanations at this point. Zuko's arc is one of the best ever put on television, and Arcann's... well, it definitely has potential, but is criminally underdeveloped (there are other people who will explain it better than I ever could).

What's similar: role of disgraced son, living in shadow of their sibling, serious injuries on the left side of face (though with different meanings), obsession with capturing the main character, having a redemption arc.

What's different: role in the narrative, role in their society, characterization, relationship with sister and mother, different end goals (before redemption), paths to redemption.