The Sleeper is a very weak and mostly useless Dying Man Piece that appears in the blog The Long Game.
He was only able to seize control of the protagonist, Shady, after gaining strength from his knowledge of his existence. However he was only strong enough to use Shady to type on his blog. Since he is weak he spends most of his time sleeping in his host and then passes on to the next, not interfering with their lives or even decaying them much, if at all. Another thing to note is that he never uses contractions when speaking.