Oh I agree about Firefly. As for Gilda, I think she started dating him because he was actually being nice. She decided to give him a shot since he wasn't being a douche towards her. I have seen this type in friends before. It wasn't a good idea, yes but I think Gilda was just tired of the fighting between Dash and Billy. Not saying she is in the right because let's face it, Billy is an ass. But again, this reminds me of a how popular girl starts being nice towards a girl only to use to her. But the girl doesn't know that. Billy is probably using Gilda. For what? Probably just to get in her feathers. And to piss off Dash because it seems he has a somewhat crush on her even though he won't admit it.
I'm also assuming that he's using Gilda to get her to cut ties with Dash.