Well, if his sister hated him, it could be due to his guilt at being in the Dollhouse with her, or to keep her from being attracted to him. (That would be awk-ward...)

He also made a joke once about Saunders and Boyd having angry scowly babies together, and I didn't think he'd joke about that kind of thing with a woman he loved. But who knows? Joss Whedon is a crafty fellow. He'll probably surprise us all. :)