LOL--Harry didn't even tumble into him now and again that I remembered. I think he was mentioned as the last one sorted in PS and then that was literally it. There may have been one other mention of him, but I can't remember him. The biggest question about him in fandom was whether he was a girl or a boy, since some people felt Blaise could go either way.

I wish the books would address the Pureblood issue. Well, this is just the type of thing Slytherin fans are interested in, but we don't get, unfortunately.