Blue Excorcist

Sorry for the dull title, but since this is pretty much what you see when you look up any promotional material for this, I didn't think it really warranted a cool title.

Blue Excorcist fanart, Rin and Yukio. Brothers who were raised by a priest, only to find they are the sons of Satan. Still, their adoptive dad instilled in them some pretty good lessons, so they fight for the side of good, awesome devil powers be damned!
It's actually a lot more fun than you'd think something like that would be. I was pleasantly surprised that Rin doesn't spend all his time moping about his daddy issues. It's a pretty fun series if that sounds like something you'd enjoy!