Disclaimer: Teen Wolf and all of its characters and elements are a product of their creator Jeff Davis and subsequently belong to him and MTV.
Likewise, Supernatural and all of its characters and elements are a product of their creator Eric Kripke and subsequently belong to him and The CW.
Notes: Not beta read. Sorry for any and all grammar/structure mistakes.
"You know, you two chuckleheads aren't that bad at this whole parenting jig." Dean jerks and the bottle in his hand hits the floor. In a matter of seconds he's across the room and pinning the source of his startlement against his kid's bedroom wall.
"What. The. Fuck. Are you doing in here?!" He manages to grit out into the face of someone he hasn't seen in ages—someone he didn't even think was alive—before a delighted squeal reaches his ears; without loosening his grip he glances over his shoulder to peer at his one-year-old who is making grabby hands at the archangel he has 'pinned' against the wall. He simultaneously feels both his blood pressure sky-rocket and his right hand spasm for the angel blade they keep stored in the trunk of the impala at what that implies.
While Stiles is a happy and sweet baby, he doesn't take to strangers, or people outside their family unit in general, well and tends to shy away from any who come near him; it had taken them ages to get him warmed up to some of their friends, including Garth and Jody, both of whom he interacts with regularly. Obviously, Gabriel has been here enough to familiarize himself with Stiles, enough that Stiles is looking at him how he looks at Sam, Cas and Dean, and Dean feels his temple fucking throb.
Gabriel simply smirks at him before snapping his fingers to disappear from his grasp only to reappear next to Stiles. "Why, visiting my favorite nephew, of course!" Then before Dean has the chance to even utter a syllable of protest or take a step forward in their direction, the fucker is casually-as-you-please scooping his son out of his crib. "What's up, Munchkin?"
Stiles, oblivious to the surrounding tension in his carefree baby world, is cheerfully babbling away (apparently a lot is up)-Ga, Ga, Gab-and patting along Gabriel's face and shoulder; Dean feels his left eye start to twitch in response. "Easy, Dean-o. We wouldn't want you to burst a blood vessel." Gabriel says, managing to somehow still sound like a raging douchebag while pretending to eat a baby's hands—how the fuck is that even possible?
Seriously?, Dean thinks to himself, staring at the sight in front of him: his son is ignoring him in favor of cuddling up to a former pain in his god damn ass—someone who has killed him multiple times and tortured both him and Sam! Fed up with this complete and utter bullshit, he takes a threatening step forward so that he can remove Stiles from Gabriel's arms only to be interrupted with the ever familiar sound of wings fluttering throughout the room as Castiel appears at his side. "Hello, Dean. Hello, Gabriel."
Cas moves forward to take Stiles from Gabriel, but stops with a puzzled look on his face with the baby pays him no mind; Dean side-eyes him as he waits for a reaction. Stiles has always been more attached to Castiel, what with Dean being off at work most of the day and Cas staying home with him, it really isn't much of a surprise. Where the one goes, the other usually follows—as fast as his little limbs allow him to crawl. Thankfully, he just seems more puzzled than offended at Stiles' behavior. It appears as though Cas hasn't worked out the fact that Gabriel has obviously been making regular visits to Stiles without their knowledge.
Dean feels marginally better, and only slightly guilty, at the fact that apparently Stiles couldn't care less that both of his Dads are now in the room and it's not just Dean. He just continues to wriggle happily in Gabriel's arms, babbling away (Dean is honestly terrified of the day Stiles' learns to talk and put actual sentences together. Holy shit.) and Gabriel… Jesus Christ, The Trickster's been wrapped around the finger of a one-year-old.
Still, Dean's about to again step forward and offer his opinion on just how not cool he thinks this whole situation is when Stiles quiets down and rests his head on Gabriel's shoulder, big brown eyes pinning his father in place with his gaze. God damn it! Dean thinks darkly, feeling his resolve shatter; he just can't say no to that face and Stiles just looks too happy with Gabriel here. And okay, fine, Gabriel did end up saving their asses with that whole clusterfuck with Lucifer and those gods. Rolling his eyes, Dean resigns himself to seeing more of 'Uncle Gabriel' in their future and tugs Castiel out behind him, snatching the long-forgotten bottle up off the floor as well.
"But Stiles—" Castiel starts, turning to go back in the room.
Dean chuckles, cutting off his protests. "I don't think you need to worry about that, Cas." Obviously, the only one in any sort of danger in that room is Gabriel himself.
That evening, when Dean has Stiles back in his crib after his bath and ready for bed, he leans down to look the baby in the eyes. "Gabriel, really? Kid, we need to work on your self-preservation instincts." Stiles offers him a wide, gummy, baby grin before smacking Dean in the face with his favorite stuffed Snoopy and letting out a pleased sounding "Ba!".