Lucius always intrigued me, especially the way Jason Isaacs plays him in the movies. He seems to be working his way into more and more of my stories too, even if it's only as a bit player.
I've never read that book by Haddon.
And, yes, I'd really rather Severus didn't take that path either. And, perhaps, some day I'll write the story of how Harry figures out what's going on and manages to get past his hurt and anger long enough to make Severus do something about it.