As usual, "Mystery Artist", it's the details that get me: the redhead's freckles, Harry's body hair (especially that little bit on his left nipple), the curls and all those lovely treasure trails. Personally, I want to think that this is an interhouse activity--for some reason, the black torso screams Blaise rather than Dean at me. But that might be 'cause I've got Blaise on the brain...
Gorgeous work.