Sam continued to smile at The Doctor, though now a little bemused at the way he was grinning and nodding. He gave Amy a polite nod at her greeting and as Gretel spoke his eye was obviously drawn to her weaponry and attire. Dean had mentioned to him that the witch hunters were here and at the mention of her name it was hard not to put two and two together. "I think you've met my brother, Dean." He told her, though it was unclear whether the statement would put her at ease or on edge with him. He wasn't sure how Dean's encounter with her had gone. "Nice blade." He added with an appraising look over the weapon.
Then the other man arrived. The one who also called himself The Doctor. Sam had assumed because of the way people seemed to be pulled from different points in time that this might be two versions of the same man, at least from the way the first one had been talking, but they looked completely different. He made a mental note to look into the that later and he fixed his face in a neutral expression. "I'd be inclined to think, especially in a place like Marrowood, that it's probably wise to be prepared for anything." He said in an even tone in response to the other mans question to Gretel about battles. It wasn't a confrontational statement, merely an observation of the uncertain nature of the place they found themselves in. Obviously by her demeanor and her attire she didn't need Sam to step in and come to her aid, but the fact that he was also carrying weapons made him feel a little like justifying it when this other Doctor spoke up. Honestly, Sam would have loved to have had the option of pacifism, but he spent too much time fighting for his life. At any rate, he smiled and shook The Doctors hand as it was offered to him. "Sam Winchester." He said. "I think you just missed that part before you got here."
Sam listened with mild amusement when The 'Bowtie' Doctor began his explanation of the two of them, it was a little all over the place and he seemed a little eccentric but Sam thought he managed to follow the gist of what he was saying, which was confirmed by Amy when she tried to simplify it. He smiled at her, then turned his attention back to 'Bowtie' Doctor who was now explaining about the pizza situation and asking to know more about him and Gretel. That could make for a quiet journey as hunters weren't exactly known for their conversation, still Sam would answer what he felt he could without giving too much about himself away until he knew a little more about the people he was with. He nodded at the end of the speech to confirm he was ready to head out.