Dogs: Bullets & Carnage, Deadman Wonderland Recommendations
Both series are heavy on characters with dark/angsty backstories, blood and death, stylized violence, and general crazy-awesome badassery. They have a very similar feel to them.
What they have in common? both are horror and action mangas, both deal with experiments on human beings with characters that have a deep past. And both stories surely will caught your attention, GREAT STORIES! written very well. I HIGHLY RECOMMEND READING BOTH!