Sam doesn't have to fake the desperation, the all-consuming fear that Dean will die and leave him alone. He doesn't actually think Patrick has any way of knowing what Dean's up to or what condition Dean's in, he knows Patrick can't know that the angels won't let Dean stay dead, but all the world's a stage and Sam's always been an actor—give him a script and a few moments to put himself in the right headspace and he'll own the show, and this is a road he's been down before. (How many roads must a man—Dean nearly dying is a monthly occurrence when it's not weekly, so Douglas Adams is full of shit as usual.)
The world narrows to fifty chips and fifty-two cards and fifty beats per minute and fifty ways Dean might be dying.
Sam's been here before, too.
Two of spades and ten of hearts. Flop cards ace of spades and fours of hearts and clubs. That gets him jack shit and the cup to drink it with and ethical issues be damned: Patrick can just go to hell.
(Better to kill demons than exorcise them: better for the hosts to be exorcised than possessed or dead, but better dead than possessed, and there's never a guarantee that the host will survive the exorcism; better for anyone to be dead than tortured with no hope of rescue, there's no way the angels will rescue anyone who isn't as important to their internal politics as Dean, and exorcised demons don't stop inflicting damage the way dead demons do. Dean hadn't had to think to come to this conclusion; he would have killed Max Miller if Max hadn't killed himself. The feds probably think Dean killed Max anyway. Ruby talked Sam around, but at that point he hadn't needed much convincing.)
If not for bad luck, he'd have no luck at all.
Sam glares at the deck.
Burn card. Turn card the seven of diamonds. Burn card. River card the nine of spades. His heart is too slow, too calm, his head the percussion section of a high school marching band competition, and he doesn't, can't, let it show. Can't let anything show except can't lose Dean.
Patrick has a pair of aces. Of course.
Sam makes soothing noises in the woman's direction (he can't remember if he caught her name, and he can't figure out what she's playing), wonders whether he'll still be a suitable host for Lucifer when he's pushing eighty, and lets Patrick see him sweat a little more while he picks up his hole cards.
Four of diamonds and four of spades.
Sam smirks at Patrick, cashes in, and exits stage left. He makes it the three blocks to the second-nearest bar he remembers how to find, orders a Jameson—Irish whiskey seems appropriate, somehow—and lets his head thump down next to the glass.
"You doing all right?" the bartender asks.
Sam turns his head sideways to see her. She's cute. "Migraine," Sam says. "I always forget how bad they get."
"Whiskey's not an analgesic," she tells him.
"Yeah, well." Shrugging's awkward in this position. "Get me another?"
When someone—Bobby, though he was expecting Dean—finally asks how Sam won the game, he's had more than long enough to script himself a reaction.