Meta: The Unlikable Rodney McKay or Why Do I Love a Fictional Character I'd Despise in RL

fingalsanteater asked me: so I just met McKay in Sg-1 and I recognized he was a main character in SGA (which I'm waiting to watch until after SG-1, though I might start it after season 7) and one half of the main pairing for the fandom. But, OMG, he was such a dick. I'm assuming he gets better (he does open up a bit the next time he's around, but he's still pretty awful and I'm so glad Sam told him she hated him because she was echoing my sentiments exactly). So, does he get... better? What is it about the McShep pairing that draws you? [link]

My answer got a bit long. :)

( These tl;dr move in herds )

What do y'all think? What unlikable characters have you come to love? Is there anyone you can't bring yourself to like even when everyone else has jumped on board? Tell me why I'm wrong and Rodney sucks, whatever. LOL