The next session of my Mutants and Masterminds campaign should be... interesting. The gist of this story is a group of friends all getting powers, but a bunch of them go villain, a bunch hero. The heroes of the bunch were supposed to be a slight obstacle to the players in some ways - trying to stop them from involving the cops, insisting on negotiation and the power of friendship, etc. - but as things turned out last session, my players hilariously antagonized the heroes for various reasons; being paranoid, offended by the newbie stealing his thing (they're both superspeedsters), and just pure superdickery.
This culminated in an admittedly accidental nat 20'd telekinetic lance at one of the newbies, knocking him out in one blow (essentially killing them, in DnD terms). They then managed to horrify the other newbie into a one-round change of sides by almost killing one of the bad guys (a persuasion 20 solved that quick). One of the antiheroic players in the group (emphasis on the 'anti') then swore to kill him later on for his betrayal.
Thing is, if he goes through with that attempt, it makes thing real interesting and solves some of my problems, to boot - mainly, that the villains ended up underpowered and nearly dead and could use some reinforcements. These guys will get their heroic friends, horrified by the actions of the player 'heroes', to join them.
The last session also featured an ice slide chase scene at twice the speed of sound through the city streets, a sentence I never thought I'd get to write.