#the voice acting and Mythals facial expression adds another layer to it

[voracusrdr]

not at all! so the qunari one is under the "Solas is helping me" option and goes like this (don't have a save to grab screenshots sadly):

Rook: Solas is helping me.

Mythal: Solas is using you. Besides why should I esteem the Dread Wolf's approbation? He rebelled against me.

Rook: But the two of you stayed close...

Mythal: Until he killed the tattered fragment of me who hid inside the human swamp witch. And wept. You are Qunari. Your people bond in different manners than mine. Can you even understand what it is to battle with someone and love them even still? That is what Solas and I are to one another. Tell me this: What should I have done when Solas turned against me after all we had been to one another?

Rook(Taash dialogue choice): Qunari go through everything you're describing. You've seen us through the Veil. Look at my teammate Taash. Shathann tried to control Taash, and Taash fought back. But when it mattered, Shathann sacrificed herself to save Taash without hesitation. Everything between them, even the mistakes, came from love.

Mythal: You have not answered my question. What should I have done when Solas turned on me?

Rook: You did the best you could. And right now, when it matters, Solas needs your help fighting the gods. So if you still love him...

Mythal: I must sacrifice myself, as your Taash's mother did? And yet. After everything... I do. And you fight for him while he waits, trapped in his prison. I find you worthy Rook

there's also a compilation for all the backgrounds/unique options here

Mythal when confronted on Titans

If you complete Harding's questline before meeting Mythal's fragment, you get extra dialogue. And a little bonus dialogue on top of that if you're playing a dwarf!

This option will automatically convince Mythal to help. Even if it's the first argument you make in the conversation.

Screenshots & Transcript below:

Rook: We know the truth about the blight. We know it came from the imprisoned dreams of the Titans after you and Solas defeated them.

I know what I am. A dwarf. A child of the Stone.

Mythal: Yes. Your people came from what remained of the Titans.

I bear you no hatred, but neither shall I apologize. It was war. Moreover, even if I did wish there had been other options, you are not the one to whom I would apologize.

Whatever pain Solas and I inflicted on the Titans it is nothing to you.

Rook: I felt that pain.

My friend, Lace Harding is another Child of the Stone. She was affected by a strange magic, and it woke up her connection to the Titan.

She felt what happened to the Titans, and the pain of that violation nearly drove her mad. I felt a flash of it, when I helped her.

Mythal: So you're saying that her pain is my fault?

Rook: I'm asking if you want the whole world to feel that pain, as the blight spreads it everywhere.

Mythal: I...do not. I find you worthy, Rook.