I agree with the previous comments regarding the use of "chan." It's such a broad term. There needs to be a widely used term that signifies the rather large difference between pre-pubescent kids and adolescents.
Anyway, the art is gorgeous. Greyback looks like something from a very enjoyable dark fantasy. Draco's socks are a nice touch, by the way; it makes the pic sadder than if he'd been completely naked.