graphic novel by jhonen vasquez *he also did invader ZIM!*
this novel is a compilation of the comic book series Johnny the Homicidal Maniac, and one of my personal favorites.
our hero Nny *as he likes to be called* is a murdering psychopath with a mission. his mission is to keep the 'thing behind the wall' in his home from coming through. Nny believes this 'thing' is from a parallel dimension and will create certain havok on our dimension. the only way that Nny can stop this from happening is to paint the wall repeatedly with fresh coats of blood, which he gets by murdering just about everybody that he finds. most deserve it. he has more than one personality as well, 2 of which keep him on a path to self destruction and one that keeps him as sane as he can be.
its gory, dark and brooding however you do get the sense that Nny has a right to do what he does and you actually get to like the guy, even with all of his indiscretions. he even attempts to 'help' *in his own really morbid way* the little boy Squee next door.
all in all i think that there is a little Nny in everyone. you can find this novel at http://www.slavelabor.com or amazon.com if youre interested. barnes and noble also carries it in the graphic novel section sometimes.