Sam was alone in his room, for once, and doing what he did most often around here: reading. Between the network and his notes on the Grounder language and the other books archived in the library, there was usually something worth reading. Even here at the end of the universe, it was his main hobby.
But he looked up from his reading when the knock came on his door, and hearing Dean's voice made him set the book aside immediately. Something in his brother's tone set him on edge even before Dean said the words we gotta talk, but he got up and went to the door, opening it. He looked Dean over, trying to pick up what he could from the subtle signals of his brother's state of mind that Dean telegraphed unconsciously, and the furrow in his brow deepened at what he saw. He opened the door wider, silently inviting Dean inside.
Thankfully, Monty was out in the woods for a while, and Kate (who had been taking full advantage of the absence of his roommate) wasn't here, either. Sam closed the door, and then looked at Dean, his expression sober. "What is it?"