"The Pure Product," by John Kessel

I just read this short story in the Best of the Best collection drawn from Gardner Dozoi's Annual The Year's Best Science Fiction. This is a strange one, even to me. You are kept interested in the story without knowing much about the main character/narrator. He seems to be immortal, which you don't learn right away, until he attempts suicide, but you gradually learn that he is trying to stimulate himself through various efforts such as tossing a Molatoff cocktail at an innocent bystander, picking up a 17-year-old girl who likes to shoplift and kill people as well. They have a wild ride for a while and then he dumps her. He seems bored with humans, though you never know what species he is or where he's from. We only get a snapshot of this immortal's life, which makes it such a great story. His attitude, his behavior, and his interactions with others all portray a man tired of living yet those words are never said anywhere. It is what we imagine might happen to something that can not only liver forever but travel through space and even time.