.....nothing. It's like she turned into a blank drone where every time I went to talk to her, she'd give those one liners, like "anything you need?", but I couldn't establish dialogue with her to have her follow me again.
Is this a glitch? Because if not, I will definitely have her stay as a vampire in that case. It was very miserable with crappy companions before her, and now that I have had this time with Serana, I can't imagine RP without her.