I remember two pairs of characters from two separate John Woo films who strike me very much as being like this: Castor and Pollux Troy (Nicholas Cage and Giovanni Ribisi) from Face/Off, as well as Emil Fouchon and Pik van Cleaf (Lance Henriksen and Arnold Vosloo) from Hard Target. In both cases, I can think of two separate fic writers who became totally obsessed with these characters and wrote a boat-load of fic that was all about them, to the exclusion of everybody else in the films. But it's difficult, because the films are not exactly terrible on their own...I mean, Face/Off is a crazy classic, while Hard Target is more of an acquired taste. For my money, though, both remain imminently watchable and full of people I'd hang with, on both sides of the moral divide. It's just that I definitely feel more of a pull towards villains, and always have. (In both cases, these characters also form sort-of couples--Castor and Pollux are brothers, one continually taking care of the other, while Emil and Pik may not be overtly sleeping with each other, but DAMN do the actors play it like they are.)

Oh yeah, and I'd totally watch an entire film about the central outlaw vampire trio of Kathryn Bigelow's Near Dark, even though I love the film itself as it is: former Confederate soldier Jesse Hooker (Henriksen again), his woman Diamondback (Jeannette Goldstein) and their daredevil, spurs-wearing "son" Severin (Bill Paxton). Paxton used to joke that they sat around between takes brainstorming a prequel, and I would eat that up with a spoon.