Maybe she's just sick of her dad. He didn't exactly seem to be to concerned for her safety when he tried to get at Jeff, after all, as opposed to Jeff having showed her real kindness and even apologizing when he took Mimi. Plus, HIM has just been bested by these guys. Maybe she wants to be on the side she senses might beat HIM.
A GIR quote: I loveded you, piggie! I loveded you!
A quote from a friend: I love the 19th century. At least when they were going to rape someone, they had class about it.
A quote from me: NO, I WILL NOT PRAISE SATAN FOR YOU, BEAR!