Exciting!!! So, the dead sister isn't really dead?
But I don't wanna wait that long!!! *throws tantrum*
😀
We'll probably not know for sure until the season finale, at which time we'll learn that they were actually TRIPLETS, sister #3 works for the CIA, and she's on the run from the agency because they believe (mistakenly) that she's been selling military secrets to some unnamed terrorist group. At the beginning of season 2, it will be revealed that they are neither twins OR triplets, but actually clones, developed by aliens who are using them and dozens of others like them, to infiltrate human society for some mysterious unrevealed reason. Finally, the series finale will have Spike waking Buffy up from a nightmare.
Spike: Is it that same dream, where you're some kind of demon hunter and I'm a vampire?
Buffy: No, this was even more frightening...
Seriously, I'll certainly watch the show when it premiers, but as of now, I'm much more concerned with how they manage to save Beckett, and what her reaction is going to be to Castle finally telling her that he loves her. If she says, "No, you don't, but thanks for saying it," I'm going to throw a bowl of popcorn through the TV screen.