Harry had been lured out into the open once before by a vision of someone he loved under threat. He had no illusions that Voldemort loved anyone at all - no one but himself of course. And there was a part of Voldemort at Hogwarts, a part that they had destroyed, but Voldemort didn’t know that. What could Voldemort be provoked into doing if he thought it was under threat? If he thought it was about to be destroyed?