It all started when Gabriel moved into the bunker. He moved in after he killed Lucifer and exposed himself to the other pagan gods as an archangel. Sam had insisted that Gabriel needed the protection that, on earth, could only be provided by the bunker. While the idea of the powerful archangel/pagan god needing protection was debatable, he couldn’t quite bring himself to say no. Later, Dean told him not to feel bad about falling for Sam’s puppy-dog eyes, as he had never met anyone, who wasn’t evil, that could turn them down. This is also what finally completely won Dean over to the Gabe-isn’t-just-a-huge-dick team.
The first incident occurred on Sam’s birthday. Dean, being the thoughtful big brother that he was, bought Sammy a cake from Baskin Robbins. If you were to ask him, he would insist that he forgot Sam was afraid of clowns. That he still thought Sam loved those places he would drop him off at when he was a kid. That’s why he chose a cake with a circle of ice cream scoops transformed into clowns with sugar cones for hats, but we all know that would be a lie. Dean walked into the bunker and headed to the main room. As he made his way past the stairs, he yelled, “Sammy, get your ass down here.” Gabriel and Dean had put together a small surprise party, and the room was already decorated with balloons, streamers, and all that party crap. Cas was there, having fully embraced his love of humanity and, as Dean walked by giving him a quick kiss, one human in particular. Bobby was already joining Ellen in a beer as they leaned back in their chairs waiting for Sam, and Jo was in the corner reading. Gabriel’s job had been to keep Sam from noticing their arrival, and to keep him out of the room. He had done this by challenging Sam to a series of board games in the library and soundproofing the room. He only lifted the barrier when he sensed Dean’s return, as planned.
When Gabriel and Sam entered the room, Dean yelled, “Surprise! Dude, what’s on your face?”
Sam grumbled something about pie-face and cheating while he grabbed some napkins from the table and started wiping his face. Cas touched his shoulder and his face was clean, which caused Sam to look at Gabriel with a glare, realizing he could have done that the whole time.
Once he was able to see properly again, he looked around and took in the decorations and his family with a big grin, “I guess it is my birthday, huh? How are none of you on a case?”
“Things are still a bit slow since we averted the apocalypse.” Bobby said, “Honestly, I think the monsters are still trying to figure out what the hell happened.”
“Good, let’s hope it stays that way.” Ellen said.
“Are you ready for cake?” Dean asked, with a mischievous smirk on his face.
Gabriel did a double-take at the sight of that smirk. He knew that smirk. It was a trickster smirk. It barely took a thought to see Dean’s prank planned out in his mind, and Gabriel was surprised at how much it bothered him. He didn’t take the time to examine his emotions, instead deciding to turn the prank on Dean. Placing his hand in his pocket he gave a small snap and the cake in the box transformed to a beautiful fruit assortment with each fruit carved into a flower, because Gabriel knew that Sam secretly loved flowers. Just for Dean, in the corner of the box he placed a small metal airplane figure, because Sam had once explained to Gabriel the real reason Dean drove everywhere he went. When Sam opened the box, the confusion on Dean’s face was priceless, but he couldn’t say anything when Sam was giving him a big hug and thanking him for remembering that Sam doesn’t really like sweets. When he found the plane later, he was bewildered but, as he couldn’t begin to figure out who would have the motivation to put a plane in with the fruit, he chalked it up to just one of those things and moved on.