Snape had suspected that he would, at some point, be returning to Hogwarts. As to what he would do ... he thought he had served his purpose rather well doing what he had always done. And being able to teach the Dark Arts with a free hand was extraordinarily tempting (although he could well imagine the disapproving look on Dumbledore's face). He supposed he wouldn't complain too much if he were shunted back into Potions. "All I have done for seventeen years is teach," he pointed out testily. "If He means to make me caretaker, I'd like to know far enough in advance to learn the trade."