Actually there are 14 episodes in Elfen Lied, one is a special episode which is almost blood-free. It's number is 10.5 if I remember correctly. It's actually a very funny episode but some parts are serious. Have you ever wondered how Lucy was captured despite her fighting prowess? It's actually in the said episode. You can try finding it, I think it's on youtube but I'm not sure. If you really ARE curious then PM me.
Its intense, captivating, beautiful, and moving all in a neat 13 episodes. I would personally recommend it to anyone.