There are a whole host of mythologies and faerie tales at play here. My first thought was that this was a dark retelling of Peter Pan, which is not all that far off the mark. This is a twisted gory ode to Peter Pan and Avalon and other faerie stories. If you really think about Peter Pan, even the Disney version, he's basically I child predator--a kidnapper. Then if you think on the original, non-watered down version, Peter is pretty cruel, he kidnaps children and sends them to war against his enemies. His lost boys are frequently killed in battle, or put out to pasture if they begin to "grow up". That's really messed up!
All that being said, Peter, is a child thief who tricks runaways, or kids from bad situations into following him into the mists of Avalon. And if they manage to make it through the mist, they're trained as soldiers in his personal army. Everything Peter does is for the Lady Modron and to protect Avalon, but it all comes at a cost. The child thief has lead countless children to the deaths.
This story had loads of deaths, battles, magic and just general craziness. All-in-all I really enjoyed it.