"I know you probably have lots more questions, Sirius, and I’m ready to answer all of them," Harry goes on, then. "But first, I need you to make an Unbreakable Vow to me." Sirius frowns his confusion at that, but Harry goes on. "I trust you implicitly, that’s not the issue. The real issue is that a lot of what I’m going to tell you will sound crazy, and I’m going to ask you to do things you may not understand or agree with. The vow will ensure that my secrets stay secret, and that you know that all I will ask of you is asked for good reasons. I will swear my honesty, and you swear your loyalty. What I’m going to tell you might make you question much of what you think to be real and true, it’ll shake your loyalties as they currently are. I need you to swear loyalty to me. Not to the Order, not to Dumbledore. To me. Are you willing to do that?"