"i do trust you. i don't...know everything. for all i know, whatever ends up happening could be worse than anything i could imagine."

And with his luck, it probably will be. Tim is screaming at him, his voice breaking, and Sans doesn't know what else to do. He knows he's doing this wrong, that Tim might end up hating him for this, but he just--doesn't know what else to do.

"it's not some kind of martyrdom, tim. i'm not gonna just stand in the path of an oncoming train because i--think i deserve it. i'm--i'm too selfish for that. i'm just gonna stand here instead. because i don't want you to go."