4. Severus "Don't Call Me Snivellus" Snape vs "Seriously" Sirius Black - Can't you picture Sirius running straight towards Severus with his wand in the air and then Severus just standing there... Then at the last moment steps aside and Sirius falls. Then Snape would AK him. (after they made sweet love :P j/k)

That has to be the best one. Although how would they shag when Sirius' is dead? *thinks* Oohh, kinky Severus ~.^