This is set in the fifth season of Stargate Atlantis, with Beckett there because he's the best. I'm not really sure what season of Supernatural, probably around the sixth season but without the soul losing but before the leviathans. So yeah, enjoy the randomness!
DISCLAIMER: I do not own Stargate Atlantis or Supernatural. Sadly. :( If I did that would be cool. And Carson would have never died.
Teyla stared through the observation window at the absolute chaos that reigned in the isolation room below.
A seven year old version of Colonel Sheppard had just launched himself off of a ramp in a toy airplane that just barely avoided colliding with an eight year old McKay's head. He was closely followed by a spiky haired boy driving up the ramp in a toy '67 Chevy Impala, who was in turn followed by a long-haired toddler wearing a plaid shirt.
"Wait up, Dean!" cried the toddler.
"You snooze, you lose, Sammy!" the spiky haired boy yelled back as he soared over McKay's head.
"Waaaaah!" cried a ten year old Zalenka. "Moje ruka bolí!"
"Shhh, it's ok," said Beckett, who looked a little older, but not much. He was examining Zalenka's arm closely with a bandage in his hand, studiously ignoring the chaos behind him.
Ronan said nothing. He was lying on the floor, shooting a nerf gun at the ceiling. He was the oldest of all of them, probably around thirteen, but none the more sociable for it.
The only other occupant of the room was a two year old boy in a trench coat, who was crouching in the corner and watching everything with wide eyes.
Woolsey, who was standing next to Teyla, was also watching with wide eyes. "How in the world did this happen?"
Twelve hours earlier, on Earth...
"I didn't want to do this, but I have no choice," said Castiel. He turned back from the window he was staring dramatically out of to face Sam and Dean in their most recent hotel room.
"What are you talking about?" said Sam, looking up from his computer. Dean looked up from the gun he was cleaning.
"It's time we searched for answers . . . in a different galaxy."
"What, you mean like Star Wars or something?" asked Dean. "Can you do that?"
"With a little help from something called a stargate."
"A what?" said Sam.
"It creates wormholes that help you travel essentially anywhere in the universe, as long as you have enough power and the right address."
"And this would help us how?" asked Dean.
"I know a place where we could find new weapons that would take the demons completely by surprise."
"I take it they don't do much galaxy hopping?"
"No. Only the angels have the power necessary to work the stargates between galaxies without the use of a very rare device."
"And you're sure the demons haven't got their hands on one of those?"
"I am sure. The humans who monitor the stargates are surprisingly capable of dealing with unexpected threats."
"So how are we going to get through?" Dean stood up and began to put his guns away.
"A bit of trickery. Don't worry about it."
Dean nodded. "You got it."
It turned out that it was actually that simple. Cas used his angel powers to fool the guards and the security, and soon the three of them were standing in front of the stargate.
"You're sure none of our enemies could do this?" asked Sam.
"Yes, I am. I've spent several months studying this place, and I'm the only angel or demon to have interfered with these humans."
"Well, let's just keep it that way, then," said Dean. "How do you get it working?"
Castiel put his hand on the 'gate and the symbols began to move. The iris retracted and soon they were staring into the wormhole. Sam and Dean looked at each other.
Dean shrugged. "We've done weirder things."
Sam rolled his eyes and stepped through.