No, Harry hadn't expected that reaction at all. But it was better than yelling. She wasn't exactly making a good case for her sanity, here, but Harry was quite used to erratic behaviour by now, so he took it fairly well in stride.

Then all of a sudden she was getting up, and he hadn't expected that either. Quickly, he scrambled to his feet and began following her down the corridor, until she turned around. He stopped short, too.

Ah, the prophecy. Yes, that was what he had wanted to tell her. "The second part of the prophecy said that one of us has to kill the other. That ultimately we both can't live at the same time. So either he kills me or I kill him." He paused, letting the weight of that statement sink in. "I have to be the one to kill him...Mum. And...I will."

It wasn't something Harry looked forward to. He didn't even know how to kill anyone. Well, of course, there was Avada Kedavra, but he didn't think he could do that, nor did he want to. Perhaps he could drop a heavy lourde (http://www.hrwiki.org/index.php/Heavy_Lourde) on Voldemort's head? He figured he could possibly handle that one. Well, he didn't really know. But he would have to work it out, because he would kill Voldemort.