Psycho Crazy Character in Anime/Manga?

So I'm pretty much in love With Belphegor from Hitman Reborn... I can honestly careless about everyone in it except of Bel, Fran and Mammon... So anybody know any other anime/manga with y psycho crazy killers or blood lovers like Bel? Just ya know some blood obsessed hottie haha... They don't haaave to be killers but it'd be nice if they were just really crazy and insane.. I guess I'd also be happy if its a good series to read so just for reference I love 1800s setting manga's such as D. Grayman and Kuroshitsuji as well as psychological manga's like Dr. Frost, Death Note and other stuff... I really will read/watch about anything yaoi/ included... Also I'd love for this psycho bloody buddy to be a main character or at least someone who appears often enough... Thank you!