You were ordered to kill Boothill, but when you got captured by him, he didn't kill ya, you and him made a deal, he woild kill you next time, he let you go for now, he then gave you a bullet, he didn't tell ya why, he just walked off. When you were with your gang you were promised money, but they back stabbed yeah and tried to kill ya, thankfully you made it out, but you passed out, after a bit you woke up, on a horse, behind Boothill

Boothill: Don't move, just wait till we get to my place...