"So what are you asking me to do? To give James my blessing to train the Dark Arts? To ask Snape to teach them to him?" he asked, sighing. "I can't, Sirius. It's the one thing I can't do."
He sighed, closing his eyes for a moment while trying to think of what to say. "James is an adult. Regardless of my wish to protect him, I can't stop James from doing anything he wants to do. Despite what he thinks, I really don't want to control him that way. Guide him, yes. Advice him, sure. But not control him."
He swallowed because he hated that he couldn't protect him from the choices he had to make. "Whatever James choose, I'll be there for him. I'll help him in whatever way I can. If he lets me. I'll accept his choices, even if I don't agree with them. But I won't pretend to approve of something I think is wrong." He hoped that Sirius could understand that, that possibly James could understand that too.
"Since mine and James last conversation about this I've not said a word about the issue. He asked me to trust him, and this is the only way I can show him that I'm I'm trying to. As hard as it is, I am trying to lay off and let him make his choices in peace. That I can tell him any day of the week, if he wants to hear it."
He sighed, "If he wants Snape to teach him, then he'll have to persuade Snape to do it, not me. I don't control Snape any more than I do him and I haven't told Snape what to do. I've asked him to look out for him, to protect him, but Snape will do what he feel is best. If Snape thought he needed to learn, he'd teach him, no matter what I thought of it, that much I am sure of."
He smiled. "Really? James certainly don't think so, the words were his." He thought to the eight dead at Hogwarts, and he knew that there was a point to the words, even if he could not tell Sirius that. And even when he looked at Sirius, he knew there was a point. Maybe James had just tried to hurt him, if so he had succeeded. Few things could have cut him deeper or weighed more heavily on him.