Sam wasn't alone when he shifted the Impala into park. The second he got the verification that Dean and Dad (or something that might well have been pretending to be Dad) were still at the coordinates that Sam had received earlier on, Sam got into contact with his mother and the two of them left in search for the duo together. Sam had hesitated about inviting Mary along at first - if the man with Dean wasn't really Dad, he didn't want Mom to be there when he and Dean put him down - but after a bit of hesitation Sam decided to go with it. She already knew that Dad was out there. If Sam didn't bring her along willingly, something told him that she probably would have found a way to get there herself anyway. It was easier like this. Safer, too. Sam could and would watch out for her if she was with him. If something went wrong, he'd be able to protect her. And if this all was real? If Dad was actually Dad? Then Sam knew that she'd want to be the first in line to see him. It was only right that she was there, even if he had his worries tagging along with them. But his worries in regards to his mother were merely a few among many. There was so much going on between Dean, Dad, his sudden half brother that he didn't even know he had showing up, Grandpa Campbell, and more that Sam found he was having a hard time keeping up with everything. He was doing his damndest, but he was still only one person. As were they all. Funny thing was, his one person was slowly expanding outward. It had been him just a year ago. Now it was him, his brother, his mother, his other brother, his Grandpa, and now possibly even Dad himself. If Sam had known, while he had been drinking himself into a drunken, depressed, stupor that things would have turned out like this...
He was getting ahead of himself. Sam shook his head, then glanced over to the passengers side of the car and shot his mother a somewhat uncertain look. "We need to put him through all the stops first," he reminded her carefully. Sam didn't know how she'd react to this situation. He was still getting to know her and, given that this was Dad they were about to run into, Sam couldn't determine what her next step was going to be. He had been far too young to remember her or her interactions with his Dad when they had both been together, alive and well. Before Azazel. Before everything.
Keys sliding into his pocket, Sam reached into his jacket with his other hand and pulled out his flask of holy water. "Here," Sam extended it to her. "I've got the silver." He sent another concerned look her way, then Sam pushed the door open and stepped outside. His tall figure turned from the vehicle and out into the open, in which Sam immediately spotted Dean. He didn't look dead. Put off, confused, and unhappy - still, not dead. A flood of relief surged through Sam, but it didn't last for long. Not when his gaze ticked over to the man standing beside him. Dad.
He couldn't let himself get emotionally overwhelmed. He had to handle all of this like a professional, even if there was this practically unbearable feeling building in his chest that urged Sam to do something more than what he was doing now. He was staring. Just...staring. Wide-eyed, body tensed, heart pounding in his chest, full on gaping like he'd just seen a ghost for the first time - that kind of staring. And that, really, wasn't very professional at all. Sam cleared his throat and looked in the other direction, already reaching into his pocket for the silver knife that he had stuffed in there earlier. He might have been able to compose himself physically, but he was having such a hard time doing so emotionally that Sam couldn't even manage to muster a coherent enough sentence to speak. Dean was alive. Dad was possibly alive. It was a lot to take in, even for him.