She only has some hints of mad scientist in her but she's not evil and will not screw over Melissa at all, in fact, she ends up liking and idolizing Melissa to a point where she decides she wants to be a knight after seeing Melissa fight with her sword.
She was already wary of Ian as he is supposed to marry Melissa, but once she really starts to like Melissa, Ian really becomes someone she ignores and insulting Melissa becomes a good way of making her hate someone, that being said, she's not a yandere nor will this become a story with a lesbian pairing, Yuri and Melissa just become friends.