While far from my favorite, I did like Flayn in the game.
She’s not quite a student or a teacher at the academy. She’s the sister of Seteth, and he’s quite protective of her.
After getting kidnapped by the Death Knight and the Flame Emperor, Flayn did join my party for a time. She was mostly a magic caster with healing and teleportation magic. She was too weak for my tastes however.
I later learned that Flayn was really Seteth’s daughter, not sister. Then my route of the game didn’t reveal that Seteth is Rhea’s brother and he’s also the son of Sothis, the goddess. Making both of them demi-gods of sorts.
I saw her one last time in one of the last battles. Since I chose to side with Edelgard, she was against me with the rest of the Church of Seiros at her aid.
And I don’t think I could have avoided killing her in the battle. Was pretty sad.
Especially as Seteth was still breathing and he saw the whole thing. Sorry, man…