Deadman Wonderland, Aphorism Recommendations
Both of the manga are about a guy who goes to a place in which messed up things happen. In both the main characters are given a special power (Rokudo a character, Ganta a sin) to fight for their life with, but they also have some inner power. They've a lot of blood in them, DW has more though. If you liked one you would definitely like the other.