Isolde on her own, is a cruel, often rude, possessive, vain, sadistic being that delights in other people's misery and pain. Even if she's taken a liking to you, even if she claims to love you. She's a demon, at the end of the day, and views most people as below her.
So there are warnings for the following things with her: extreme violence, body horror, torture, manipulation, murder, guro, misandry(and the strange sort of implied misogyny full-throated misandrists tend to have), physical/emotional/spiritual abuse, questionable/non sexual consent, and all the broken boundaries and other stuff that comes with it. If you want Isolde to be played with less of those traits, I will gladly do so upon request. Or if you just don't want to play with her character, that's cool too.
So there are warnings for the following things with her: extreme violence, body horror, torture, manipulation, murder, guro, misandry