Vivian was a somewhat major villian in the first season. She was originally a student of Merlin and made herself a servant of the corrupt Holy Knights taking over Liones.
All of it was to make Gilthunder her husband. Keeping his love Margaret Liones as a hostage until she was defeated by Merlin herself. She was a decent magic user but easily defeated by her teacher.
She pretends to be a male mage named Gilfrost after her defeat so she could keep an eye on Gilthunder. I definitely didn’t see it coming.
And she magically kidnaps him when faced against a hopeless fight with Grayroad of the Ten Commandments. She’s apparently killed by Ludociel who murdered her as a favor to Margaret in exchange for using her body as a vessel.
I was disappointed to learn she survived. Thanks to Dreyfus, whom she decides to “love” instead. At least she left Margaret and Gilthunder alone after that, crazy witch.