"That's why we need to make a plan. Do more research, even if the very idea is painful. We need to find out exactly how we were brought here, and how we get back. We need to know how to kill Voldemort. And, I think I should go back alone. I can go back right before I was taken. James and I were out on a mission, so I won't risk running into my other self. I can give Dumbledore the information. I'll tattoo it on my body if I have to. Then I'll try to get back here. If I can't, I'll just off myself somewhere discrete and the other Sirius can live a life where none of this happens."
He'd been thinking about this plan pretty obsessively for the last week. It had to work. It just had to.
"That way, you and James will be safe even if I fail. But if I don't, then this whole thing will never have happened. If Dumbledore defeats Voldemort in 1980 then things will change so much that they will probably never need to do the hex! We could fix all of it, all the death, Harry growing up like that, all of it, if Dumbledore kills Voldemort before any of it can happen."