My favorite quest oat... I actually cried when I first did this quest.

As yall know, vivienne was cursed before she was even born, by a creature that was jealous of her parents, and nothing really happened to her until the day she turned 15, it was that day the curse started becoming worse and worse, making her look like a humanoid bird, and she can only hide it with magic temporarily since it is getting worse lately.

It’s up to you how to deal with her.

source: the witcher 3 blood and wine.