Mary Campbell's father was not Samuel Campbell. Of course, not even Deanna, Mary's mother, knew that.
Only one person (well, two, if Joshua by the tree counts) knew that divine blood coursed in Mary's veins, and Mary grew up a hunter instead of a thief.
That's alright, though. Her sons were thieves. Good ones, too.
Dean Winchester isn't aware that he's a better-than-usual thief, or that he skates by on the skin of his teeth, or that all his last-minute-escapes aren't always down to learning-by-doing.
Sam is. What Sam isn't sure of is why.
Dean and Sam meet their little brother after he's been resurrected (like Dean) and figure out straight-away that he's not the gosh darn, so good to meet you! ghoul they'd known.
Adam's a punkass smartmouth who isn't in awe of them. He's annoyed with them. He fits right in.
Also, his dad isn't John Winchester.
"Why is that I have to die - twice! - to get any family other than my mom?" Adam yells at the sky. "Huh, oh great and power lord of thieves? Where the fuck were you! I went to your fucking training camp and I did exactly what should've made you proud! But you cast me out, back into - into, fucking apple pie and normalcy, and it was grand, you fucker! It was fucking grand until it got me killed!"
Dean and Sam look at each other, then at Castiel, who doesn't actually shrug, but Dean gets that impression, anyway.
Adam ignores them to keep shouting at clouds. "What do I have to do!" Now it sounds like he's holding back tears, and all Dean wants is to make everything better. But he can't.
"Aren't we being easy-to-find?" Sam murmurs to Castiel. "I mean - this is pretty obvious."
"No," Castiel replies. "Adam will not be found unless he prays specifically to an angel."
Dean and Sam share another look. "You found him," Dean says.
Castiel doesn’t actually smirk, and Adam turns on a dime to glare at him. “Oh, you fucker,” he hisses, and stalks over to punch Castiel right in the mouth.
So Adam isn’t Dean and Sam’s little brother. He’s actually their uncle.
And Castiel –
“Were you ever an angel?” Dean demands with a glare. “Have I ever actually met Castiel, angel of that fucking douchebag God?”
Not!Castiel, whose name Adam still hasn’t said, actually does smirk. It’s creepy. “Surely if Gabriel can take a leave of absence and go play with the pagans, I can, as well?”
Dean shudders, because Castiel sounding sarcastic is friggin’ frightening.
“So, what’s your pagan name?” Sam asks.
It’s Adam who snarls, “Hermes.”
So, two pagan gods, two hunters, and a one-time lightning thief walk into a bar.
“Bro!” Loki hollers, pulling Hermes into a massive hug. “How’s it shakin’, dude? I’m glad you dropped the undercover gig – it was gettin’ annoyin’.”
Hermes hugs him back, laughing.
Dean and Sam share another look. Adam rolls his eyes.