[Vash makes a face. Putting this sort of thing into words isn't easy. He knows Pure Vanilla is trying, but he also knows that there's only so much he can do. This isn't just Vash being stubborn in this case. Love is one thing. He might still struggle with it, but he's coming around the concept. Forgiveness... is an entirely different minefield.]

You just - [He shakes his head once. His mouth opens, then closes. He knows what he wants to convey, he just has to figure out a way to do it without hurting.] It's not your place to forgive me. You weren't there. You didn't have loved ones there. Maybe I'm not a monster, maybe it's not my fault but... you can't be the one to determine that.

[With the words out, Vash hangs his head. He feels guilty even denying Pure Vanilla this, but it's all so... complicated.]