The one who seduced you and fucked you over and broke your heart in a million pieces and laughed about it: QAF and Firefly for different reasons
The old flame you don't see very often any more but whom you still really enjoy getting together with for a few drinks and maybe a pleasant nostalgic romp in the sheets: Buffy
The mysterious dark gothy one whom you used to sit up with talking until 3 a.m. at weird coffeehouses and with whom you were quite smitten until you realized he really was fucking crazy: Lost
The one you spent a whole weekend in bed with and who drank up all your liquor, and whom you'd still really like to fuck again although you're relieved he doesn't actually live in town: Heroes
The steady: Supernatural
The one you repeatedly cheat on your steady with: CW_RPS, although they know about each other, we really are more polyamorous
The alluring stranger whom you've flirted with at parties but have never gotten really serious with: House
The one you hang out with and have vague fantasies about maybe having a thing with but ultimately you're just good buddies 'cause the friendship is there but the chemistry ain't: Veronica Mars
The one your friends keep introducing you to and who seems like a hell of a cool guy except it's never really gone anywhere: Sarah Connor Chronicles
The one you slept with on the rebound who still smiles at you, yet you have no interest in any more: The Office and Scrubs
The one who's slept with all your friends, and you keep looking at him and thinking, "Him? How the hell did he land all these cool babes?": Bandom, just does nothing for me.
The one your friend has fallen for like a ton of bricks and whom she keeps babbling to you about on the phone for hours, and you'd be happy for her except you just know it's going to end badly: Twilight, I have two non-fandom friends who talk to me about this book and if I hear one more word from either of them! I swear.