Sam had noticed it starting to grow worse. Dean had already fetched anything Sam tried to toss in the trash can, scratched behind his ear, yelled at a mail man, and now he was eyeing the sandwich Sam was eating with his best begging face.
"Jesus Dean are you just gonna keep staring at me while I eat?" Sam said with an annoyed tone.
Dean’s eyes flicked up to meet Sam’s stare, “What- oh- I… Sorry.” Dean shrugged sheepishly, reverting back to his normal self for a moment, “This whole dog thing- you know- it’s…uh..” Dean trailed off with a nervous laugh. He moved from the table over to one of the beds in to motel room.
"Yeah. Whatever." Sam just chuckled and continued to eat his sandwich.
Sam looked back at Dean about ten seconds later and he was staring with the same look again.
"Dude seriously- cut it out!" Sam tucked his sandwich behind his back.
Dean looked down with a dejected look, mumbling sorry to the floor.
"Hey- don’t get all sad puppy on me. You have your own sandwich!" Sam tried.
Dean just stared down guiltily.
"Dean, come on don’t be like that."
"How about- how about a tummy rub? Hmm? Dogs like that right?" Sam suggested with a chuckle.
Dean looked up, face seeming to perk up at the idea.
"Aww Dean just wants his belly rubbed doesn’t he." Sam cooed, setting down his sandwich and walking over toward the bed where Dean was sitting.
Dean glared at his brother, “Don’t patronize me, bitch.” But he still leaned on his back when Sam came over.
"Oh shh- you’re just a big softie aren’t you-" Sam laid a hand on Dean’s stomach and started to rub lightly.
Dean smiled and kicked his foot slightly, stretching out even further. It felt really nice but…it also kind of tickled.
"Who’s the bestest brother in the whoooole world." Sam teased.
"What’s so funny?" Sam asked, still rubbing his brother’s stomach like a dog.
"Nothiihihihing!" Dean insisted, fighting the urge to curl in on himself.
"Are you…okay?" Sam asked with slight concern, pausing his hand and drawing it back from Dean, who immediately shot him a sad ‘why-did-you-stop’ look.
Dean nodded quickly and Sam shrugged, then grinned and started to rub Dean’s tummy again. Dean squirmed and giggled but he didn’t try to move away.
"What’s up with you- how come you keep…" Then Sam’s grin spread, "Are you still ticklish?"
"What? No." Dean shot back defensively, "Of course not."
"You sure about that?" Sam chuckled, his hands now deliberately trying to poke and tickle Dean’s stomach.
"Yehehehes I’m sure- hahaha- I’m suhuhure!" Dean laughed.
"Then how come you’re laughing?" Sam raised a brow in amusement.
"I-I hahaha sh-shut up hahaha bihihitch!" Dean was squirming and kicking his legs, hands switching between curling into the bed sheets and flailing a bit. Sam noticed that Dean could easily put a stop to this if he wanted to, but he was actively trying to KEEP himself from pushing Sam away or moving.
"Alright, whatever you say dog boy." Sam rolled his eyes and stopped his belly rub. He couldn’t help but notice Dean’s disappointed look when he stopped.
After the case had been solved the brothers returned back to the bunker. Dean had gone back to his room claiming that “since he wasn’t a dog anymore he needed to take a cat nap”. Sam was feeling bored and a bit playful; combined with a hint of curiosity this was a dangerous mixture.
Sam made his way down the hall and slid quietly into Dean’s room. Dean was still not out, just laying there, so he greeted Sam with a smile as he entered. “Can’t you let me get my beauty sleep?” He joked.
"Doesn’t look like you were doing much sleeping." Sam countered, "Something on your mind?"
"No no, nothing in particular." Dean shrugged off his former thoughts.
"Maybe a little belly rub would help you relax." Sam teased, wiggling his fingers at Dean as he sat down on the bed near his brother.
"Shut up." Dean replied, "It’s not my fault dogs like that kind of crap."
"I don’t think it was just doggy Dean who liked it."
Dean’s eyes narrowed, “Sammy…”
His little brother just grinned at him, “And I don’t think it was just the belly rub you liked.”
Dean was now full on glaring at Sam, a light pink color heating his cheeks, “Don’t know what you’re getting at Sammy. Just let me sleep.”
"Hmmm… Or I could do this." Sam laughed and his finger flew to Dean’s stomach and sides, squeezing and tickling and poking; Dean’s head was thrown back in laughter and his whole body was squirming and jolting with the electric-like sparks that the tickling drew through him.
"Sahahahaham! Nahahahaha Sammyhehehee!" Dean laughed.
"How could I have forgotten you were ticklish?" Sam snickered.
"I’m nahahahhahahot!" Dean insisted.
Sam just laughed, “Hate to break it to you, but I think you might be. Just a little.”
Dean just laughed in response, squirming from side to side as Sam’s fingers raked up and down his ribs and spidered all over his stomach. Again, Dean wasn’t actually fighting back. And, he wasn’t actually telling Sam to stop.
Sam tried all the weak spots he could remember from when they were kids, just under Dean’s rib cage, his hips, under his arms, the sides of his neck, and even a squeeze or two above his knees, which made him kick out. Sam was not disappointed in the degree of reaction from Dean. The older Winchester looked so happy and carefree as he laughed, maybe that was why he was enjoying himself, he felt like a kid again. Sam smiled and laughed along with his brother, finally slowing his tickling to a stop after a solid ten minutes of nonstop tickling his older brother.
"How ya feelin’?" Sam asked as Dean caught his breath.
"Peachy." Dean replied sarcastically, though there was less venom in his words than usual, and his smile was lingering.
"You seemed like you were having fun." Sam shrugged.
Dean hesitated, seeming unsure of himself, but then his expression changed to predatory, “You know, I seem to recall that you were pretty ticklish when you were little Sammy…”
Moments later, Sam was bolting out of the room, Dean close on his heels and both of them laughing.