I think this episode is the first time we see Sam out-and-out having fun. It's telling that our first sight of Sam in Hell House is Sam sleeping soundly in the car while Dean drives. It's a subtle reminder of the opening of Wendigo, where Sam's sleep was haunted by his dreams of Jessica's death. Here, his sleep is peaceful, so much so that he doesn't wake up while Dean sticks that spoon in his mouth. After the intensity that was Shadow, this makes sense. Sam hasn't forgotten Jessica - I doubt he ever will - but he is beginning to move on. The change in his motivation is subtle through the first half of the season: he's gone from searching for John in order to hunt down Jessica's killer, to searching for John because John's his father and he wants to reconcile. But in Shadow, he finally saw John again. It was a brief meeting, but a significant one. I'm not suggesting that Sam wants revenge any less, nor that he's about to give up the search for John. But that meeting, which ended with John's promise that Sam would get to join in the fight, and a voluntary parting, takes some of the urgency out of both quests. The more light-hearted theme of Hell House is the natural result.
Sam's evident embarrassment when he's telling Dean about the haunted house makes me think he is expecting this particular investigation to be a bust. Maybe Sam, like Dean, is ready for a vacation, and picked out this gig, which sounds like a practical joke from the get-go, as an oblique way of getting a break. Certainly, though he initially rejects Dean's desire for a prank-war, Sam gets into the spirit of it quickly enough.
In my mind, Sam is the clear winner of the brothers' prank-war. Dean's pranks are, well, kinda generic. But each of Sam's jokes are appropriate: they show he's given it some thought and does something calculated for maximum effect. I mean, as an opening salvo there are a dozen simple pranks he could have played on Dean. But he chose to mess with Dean's music, and in his car. Dean calls it weak, but I think Sam's right: score one to him.
There are limits to the joking, though, and Sam makes it clear there's a line he's not willing to cross when he refuses Dean's childish "double dare" in Mordechai's house. He's willing to play the game, he's enjoying the game, but he's not about to let it escalate to the point of putting either of them in danger. I wonder if that's a peek into their childhood: is it possible that their childhood prank-wars did occasionally go too far? If Dean really did put Nair in the shampoo, I think so.
But Dean's second prank is on the mean side, and it's also potentially dangerous, given that they're working a job. Not very dangerous; it's just itching powder, after all. But if Sam were distracted at the wrong moment...these boys live dangerous lives.
Which leads to Sam's next prank: the super-glue incident. He could have super-glued a shotgun or the Impala's wheel and it would have been just as funny, but Sam picks a beer bottle in a diner, ensuring they're in a safe setting. And, I think this exchange following the prank illustrates just how perfect it was as a prank to play on Dean specifically:
DEAN: I barely have any skin left on my palm.
SAM (sniggering): I’m not touching that line with a ten-foot pole.
The sexual implication is obvious, and I think poor Dean's gonna be jerking off with his left hand for a while.
Even Sam's joke on the
Lone Gunmen two website nerds shows the same thoughtfulness. He remembered their mention of wanting a book-and-movie deal, knows that there's no chance it'll happen and that they're dumb enough to fall for the joke. That phone call is nothing less than inspired.
On a more serious note, Geek!Sam is much in evidence in this episode, too. From his recognition of the symbols painted inside the house (and notice - as Dean does) that Sam knows this stuff; he didn't need to reference the books for those symbols, to his figuring out Mordecai's true nature in a leap of logic worthy of Fox Mulder. This is why I love Sam: guys with brains are hot! </shallow moment>
I do find it interesting, though, that Dean doesn't seem to know the story Sam tells him, about the monks creating a golem from their thoughts. I mean, I figure they had the same basic education in the paranormal stuff, and in a couple of episodes Dean has demonstrated that he knows things Sam doesn't, but here it's Sam who knows the story. It makes me think that, despite his apparent embracing of a "normal life" in those four years away from his family, Sam kept up with his studies in that area, too.
Lastly, to return to what I said at the beginning, Sam's interaction with that pair of nerds is another illustration of how much he's changed over the course of the season. Remember how he behaved in Wendigo when he thought Hayley was getting in the way of the job? Contrast that with the way he behaves when he and Dean first run into the nerds in the house. At the beginning of the series, Sam would have told then they were being idiots and kicked them out of the house himself, if Dean didn't stop him. But he's changed. He interviews them, satisfies himself that they know nothing, and just has fun with it.
Nice to know Sam can have fun once in a while.