parent trap au: Michelle and Lee Unwin divorce over Lee’s involvement in Kingsman when their twin sons Eggsy and Gary are still young, Michelle keeping Eggsy with her in South London, Lee and Gary moving into a Kingsman-issue house a few streets from the shop on Saville Row.
Eggsy and Gary grow up separately and finally meet 15 years later at a police station, Eggsy for stealing a car and Gary for drunken disorderly. Gary’s always wanted to be a Kingsman to make his father proud, but his heart’s not in it, and deep down he knows he doesn’t have the aptitude, not like Eggsy, with his brash accent and illustrious criminal record, Eggsy who will never even be considered for Kingsman because Chester King is a snob.
It’s Gary who proposes a switch: he’ll teach Eggsy how to behave like a gentleman and get into the Kingsman interview, and in return, he’ll assume Eggsy’s identity so he can spend time with Michelle and Daisy, because Gary is so jealous of how close Eggsy is with his family. Lee’s always provided for him, but he’s always away on missions, and the house is too big and quiet.
(”We both have our work cut out for us,” Eggsy mutters and tries for the umpteenth time to tie a perfect Windsor knot as he watches Gary walk from one end of the room to the other in his street clothes. “No no, slouch more! Anyone with eyes will be able to tell from a five-mile radius that you’re a posh git if you parade around like that.”
“How do you move in these jeans without tripping, honestly,” Gary complains but gamely attempts to unbend his ramrod straight posture and hunch his shoulders.)
They manage to pull off the deception, but their plan is not without its snags - Eggsy’s dog J.B. growls and hides whenever Gary enters the room, like he knows his master isn’t who he says he is, and Lee’s colleague and former mentor has the most alarming habit of staring at Eggsy as if he’s on the cusp of figuring him out. Eggsy stares back unabashedly, because fuck him, Harry Hart is a smoking specimen of a man.
(”How do you even function around him?” Eggsy hisses into a payphone in the middle of a noisy pub. He suspects Harry’s bugged his mobile, and shit, that shouldn’t be so hot. “He’s so - fuck - the second he walks into the room, all the blood in me head goes right down to- “
“I don’t need to know your fantasies about one of our oldest family friends,” Gary interrupts hurriedly. It figures that Gary’s straight as a pin, and his twin ‘goes in for a bit of that’, as Eggsy calls it. “How’s it going in Kingsman?”
“Oh, brilliant. I’m down to the last five candidates. Merlin says Roxy and I broke the height record for parachute deployment in the skydiving test.”
Skydiving, Gary thinks with a shudder and knows he would have failed out weeks ago. “Listen,” he says. “There’s something you should know. Mum told me today that she’s marrying Dean. The wedding’s in two weeks.”
“Shit fuck,” Eggsy swears. “Dean’s a right bastard. You’ve got to stop them.”)
Gary’s seen Lee’s Kingsman medallion that Michelle still wears around her neck, and after one too many scotches, Eggsy learns that not a day goes by that Lee doesn’t regret walking out of Michelle’s life. Families that love each other should stay together, they agree.
Now Gary and Eggsy’s mission, should they choose to accept it, is to reunite their parents before they throw away their chance at happiness for good. Between an international spy (not quite yet) and the best big brother in the world (“In the universe, Gary!” Daisy insists), their marks honestly don’t stand a chance.