Damage

Everyone knows about guardian angels - and Nezeq knows he should never have been made one. He's a demon, after all. So instead of protecting the human Joshua, Nezeq tries to kill him. And fails. That's his first mistake. His second mistake is in coming back to finish the job. There's not going to be a third mistake. Originally published in Dragons, Knights and Angels magazine, Damage won second place in the 2006 Reader's Choice Award for short fiction.
Damage is also part of the Seven Angels Short Story Bundle, along with Even A Stone, Winter Branches, Hired Man, and eight bonus shorts.