"Not only the unforgivable changes you," Harry answered. "Anything that doesn't, I'm fine with. I can see the need, though I know there are plenty of other lethal spells that aren't dark in nature."
"Some are even taught within the Ministry, though not until the very last leg of training so James hasn't got to that point yet. We're working on getting him trained faster than the others, but he doesn't like Moody, and doesn't want to train with him."
He closed his eyes. "I've not told him not to learn other magic, other means to kill. I've only told him that I don't want him to learn the unforgivables, the kind of magic that would taint his soul. I want him alive at the end of this too, but I want it to be him."
He looked at Sirius. "How far would you go to keep him him?" he asked. "Because I had Ron, Hermione and Ginny, but not until Ginny told me she was leaving did I realise how bad things were getting. If things got that bad, if he changed that much, would you be prepared to do what she did? If it was necessary to keep him him."