Saw Soul Taker. It's dark and abstract, still it has charm in some way. It's about a guy (bad with names u.u") who gets killed by his mother. The shock, and the will to live on changes him into a monster. He gets to know that he got a sister somewhere, so begins to travel looking for her, while everyone wants to hunt him down for his genes.
As writen, it's quite dark, and they show some abstract pictures from religion and what humanity is. For example his ultimate attack makes a big cross as the target explodes in it. I wouldn't say it's an average anime, but I found it interesting.