For a moment, Sam thought that the voice had just been another figment of his imagination. That maybe Dean had come back to give him a hard time about his attempt at escaping. The voice, however, didn't belong to Dean. It was different; it was Bobby. Sam fell to a halt in his steps, eyes screwing shut in frustration. He figured it was time for old hallucination Bobby to come along and criticize him the same way that hallucination Dean had - violently, angrily, and without pity - but there was something about the tone of Bobby's voice that made that resigned annoyance of his fade. Sam cautiously turned, immediately noting the shotgun that was being held carefully in Bobby's arms. Not fake. Real. None of the others had come at him with an actual weapon yet. Just bitter words and glares of pure, undeniable hatred. This was different. More importantly, the look on Bobby's face was different. His eyes weren't cold. Not even the slightest. Sam didn't know why or how he could be sure that this was real, but he knew that it was. That was the only thing that kept him from turning his back to Bobby and continuing on with his hunt for some wheels. This Bobby was real. And in spite of their current differences, Sam really couldn't just turn his back on him. Especially not when there was a weapon involved. His gaze lingered on the gun for a long moment; Sam couldn't exactly tell as to whether or not Bobby would actually shoot him. He knew what he wanted to believe, certainly, but...
"So that's it, huh?" Sam lifted his eyes. He didn't look angry or disappointed that Bobby had caught him out. There was an underlying feel of sadness in his expression, making him look even wearier and emotionally worn through than he already was. He didn't want to do this. Not with Bobby. Not with anyone. Yet the fact that Sam knew that they were going to have to fight it out in order for him to escape was a brutal truth. Sam didn't want to fight Bobby. He was family. Always had been and always would be. But that didn't mean that they weren't going to end up spilling a little blood here because of their different perspectives on the current situation. It wasn't Bobby's fault - he didn't understand how important the demon blood really was - yet Sam was going to do what he had to. It was the only way to stop Lilith and save them all. Not just Dean and Bobby, but the whole entire world. Lilith had to die. This was bigger than Sam's obsession with her (though that did help fuel the fire). She had to be stopped now. Plain and simple. And if that meant that Sam had to exchange a few blows with the people that he loved in order to see to it that the bitch burned? Then so be it.
Sam held his hands out at his sides, showing that he was completely unarmed. Not that it would have mattered. "You gonna shoot me, Bobby?"