i was once afaird of power. the vision of two ogres beating each other into pulp is a nightmare i often had after fighting a kid down the street when i was five. i thouroughly enjoyed it, won, and was then punished for fighting even though he wanted to.
also being abducted by aliens was a weird scence when i turned around in the shower. consequently i always shower with my back to the shower head.
as far as S/M goes though the most extreme fantasy i've gotten off with always end in "American Psycho" style stuff while i masturbate to death metal to keep my load from going.