As I was implying in the paragraph above say you do pick an elf (so long as they dont looklike the Non-blue Navi from Avatar), humans should be less likely to trust or give you quests.
Extremis is also the name of a bioenhancement process that turns some of the movie's humans into turbocharged heavies who glow with evil energy and looklike zombies.
The American writers Temple most resembles are Richard Price, Dennis Lehane and George Pelecanos all of whom look squarely at the depths of depravity that humans are capable of (and write like fallen angels).