I wish I could play an antagonist in such a swift manner. I'm not quite at that cunning though. 

I frequently gravitate towards the more antiheroic types of character It's usually those who side with villainous factions on the promise from said villains that their personal (sometimes nobler) intentions would ultimately be satisfied by their involvement. Such as one character I sided with a faction bent on pretty much wrecking the omniverse in return for the return of documents hinting to the fate/whereabouts of an estranged/missing relative. Of course, I ran that one with the intention of my character betraying/sabotaging the villains once he got what he needed back from them, and thus helping to thwart their plans.