#hm. red haired Tensei.... all the jokes about how *hot* he is....

[pocketramblr]

If the ask games is still open: A sibling swap in where Touya, Fuyumi and Natsuo are all Iidas (and thus Tenya's older siblings), while Tensai is Shouto's only sibling.

Oh wow this produced such healthier family dynamics I'm sure-

1- Tensei is, of course, Rei and Enji's pride and joy. When he's born, Rei immediately tries for another but it's too soon for her body, and she miscarries. Tensei's quirk isn't quite as strong as Enji hoped for, but he's worried about Rei being able to carry any child at all again -what if the last baby had been "too hot" for her cold body, he really should have gotten more information on genetics, pregnancy, and quirks before he decided to do a mini eugenics experiment but you live and learn ig- so he trains Tensei carefully. Tensei thinks being a hero is Cool™ and is more obedient to his parents than Touya would be.

2- still, over the years, Enji begins to think it still won't be enough. Perhaps, with how good Tensei is using support gear to keep up his health, with how well he works with others, he'll lead the Endeavor agency and do far better than his father, break his records cases. But... He won't surpass All Might. And Rei always wanted more children, and she's 33 this year and after 35 isn't it supposed to be riskier... Why not try again? And then Shoto is born the week Tensei gets into UA, and he's perfect.

3- Meanwhile, the Iidas have always had big families (if you're cynical: gives them a better chance of having as least one in the generation with an engine quirk to keep the brand going. If you're less cynical: they're rich enough to care for as many children as they want and since they remember childhoods with siblings and cousins, they want the same for their kids.) Touya ("Mercury") has engines on his ankles, Fuyumi ("Nike") on her shoulder blades, Natsuo didn't inherit the engine quirk, and Tenya of course has his calves.

Now... You know how Dabi gets carsick when Spinner drives? Great ok because now his body is the car. And he doesn't have brakes. So even here, his quirk and body do not get along.

4- Tensei adores his baby brother just as his parents do. He's so excited his second year when Shoto manifests his quirk. But that said, he's a busy kid. He's interning at his father's agency after school, but taking on more responsibility there. He leads a lot of people, and he's very good at it. When he graduates, he's the second in command. When he's twenty, he's practically in charge. His father is at home more, after all. He thinks nothing of it... Until he visits unannounced one day, and hears shouting from the training room, opens the door just in time to hear "he's already five" and have the scent of vomit hit his nose.

Enji's hand is raised to hit Rei, though it falls on seeing Tensei. His expression shifts, asks if something is the matter, an emergency. Tensei stares, jaw slack. It's quiet as the whole picture sinks in for everyone there. Then Shoto gags, and Tensei moves to go to him. "Trainings over." He declares. "I'll get him cleaned up, we'll talk after dinner."

"Tensei-"

"We'll talk after dinner, Endeavor."

5- Touya, to no one's surprise I'm sure, sucks at working in teams. Given that is Idaten's whole shtick, Fuyumi steps into a team leader role instead. But her quirk is far more limited than her brother's, really only lets her go up and down, so on the field Touya is playing the main character while Fuyumi organizes his backup dancers. She's too nice to admit if it bothers her, but she and her parents have quietly planned to have Tenya take over in her role if he has a knack for it, then inherit the agency, because even Fuyumi doesn't have the patience to want to babysit her older brother forever. They hope that Touya's attitude tempers out by then.

Instead what happens is Stain attacks Mercury who frequently goes off on his own. He, improbably, survives. In the hospital, he calls Tenya to talk to him alone. He is not there to give Tenya his hero name, in fact, it's the opposite:

Touya: "don't you dare take my hero name, I know you pick them next week, and Mom and Dad are idiots if they think I'm retiring just because they tell me to."

Tenya looks at the scope of the injuries. But he looks up to his siblings and is relieved to not have that pressure on him, so he agrees.

Touya: "great, now even more important: don't you even think about taking my revenge. I'm going to be the one to kill Stain, and if you take that from me I'll kill you too, and then Fuyumi will kill me and die of a broken heart, and Natsuo can't pass on engine. Do you get what I'm saying?"

Tenya: "... That continuing the cycle of violence and revenge would destroy our family and ourselves, instead of bringing justice?"

Touya: "oh my god no I don't care about that. Just know that if you even look in Stain's direction before I put his pieces in a body bag, you're going to be in there with him."

Tenya agrees to not go after Stain... Though he does think of backup plans.