Hugh: So, the blond chick is a vampire now?
Chelle: Yes, Katherine turned her.
Hugh: And, Katherine is the evil twin?
Chelle: Yes. Well, no; she and Elena aren't actually twins, Elena is her doppelganger.
Hugh: Her what?
Chelle: Yes, they're twins.
A bit later...
Hugh: How is the blond chick stronger than that guy (Damon)? He's older. I thought older vampires were stronger.
Chelle: Newborn vampires still have human blood in their systems so, they are stronger than even older vampires for a while. Then, they are regular-strength vampires who get stronger as they get older.
Chelle: Wow. I think that was the geekiest thing I have ever explained to you.
Hugh: I was just thinking that same thing, myself.
The lesson here? After eighteen years together, a couple starts to share a brain. Although, if he was also thinking that Ian Somerhalder is super-hot, we could be in trouble.