Prostitution as both punishment and an attempt at blunting his feelings by glutting himself on sex. This makes so much sense, especially in the aftermath of the war and the belated, and far too late, acknowledgment of an unrequited love.
And your Krum is equally vivid. Not just a variation on the theme of Snape, but a character of his own right and capable of taking care of himself and of waiting for Draco to stand on his own two feet before accepting him.