Annnd I wrote the thing. Sort of. It kinda got out of hand.
The first year they’re just Fred and George, except when occasionally they’re Gred and Forge, but it’s not too long before Snape just stops trying to tell them apart and just treats them as the joint entity “Weasley,” who happens to be in two places at once.
The next year they take turns attending first-year Potions class as Barry Weasley, the glasses-wearing Weasley cousin who missed the Sorting Ceremony because he tried to swallow three chocolate frogs at once on a bet from his twin cousins and got sick.
Snape has a choice between asking questions about Barry and punishing Fred and George for tormenting their cousin, and punishing Fred and George wins out. At this point, it’s not really that weird–the Weasleys do tend toward large families–and any excuse to give the twins detention is basically the sort of thing you could put under a box propped up with a stick on a rope and a “TOTALLY NOT A TRAP” sign to catch Severus Snape.
So he figures Barry Weasley is real. He comments on the boy’s resemblance to Fred and George, and Barry nods and says “Everyone says that. I could fool everyone but them, except eventually people figure out there’s only one of me.”
Snape doesn’t have much cause for complaint. Barry is not a difficult student (the twins are, at this point, quite happy with the joke for its own sake and so don’t risk the Barry persona on tormenting him), perhaps a bit prone to letting his mind wander (it helps that George is actually interested in Potions, and uses the second run as an opportunity to experiment), but there have been no outright disasters centered around his cauldron, which is a lot more than can be said for the twins.
The next year is Fred and George’s third year, Barry’s second year, and Ron’s first year. They don’t take Ron entirely into their confidence … but they do let on that they’ve invented a fictional “Cousin Barry” to mess with Snape a bit, in case Snape asks, but Snape doesn’t ask.
He does mention Barry Weasley to Barry’s supposed Head of House, but by pure luck he manages to do so when Minerva is sufficiently preoccupied by that late night with four first-years sneaking out after curfew, and she hears “Harry and Weasley,” and nods, and asks him something about a Gryffindor fifth-year she’s concerned about, and, well, that basically settles it.
Fred and George run into a minor difficulty in that they don’t have a free period coinciding with “Barry’s” potions class, but they get lucky enough to have History of Magic during that class, and Binns wouldn’t notice if Fred or George set the classroom on fire, much less if Fred or George is always absent.
Fred and George are at this point quite satisfied with getting “Barry” through seven years of Hogwarts without Snape realizing he’s fictional, but then at the beginning of their fourth year Snape is absent from the Sorting and the Welcome Feast and … well. Opportunity beckons.
Since Fred and George are pragmatic about which elective classes they take (they’re much more interested in independent study directed toward magical jokes and pranks), they have several free periods and it only takes a significant look between them to agree that, yes, they can absolutely handle being one more person just for Potions class.
They’re a bit more advanced at their magic now, and a bit of diluted Shrinking Potion and a Freckle Charm create Barnaby, Barry’s younger brother. There’s a minor concern with Ginny being in the same class, and more importantly, Operation Barnaby is still in the planning stages when McGonagall hands out the schedules and they realize they have Transfiguration during the requisite class period and McGonagall will definitely notice if a twin is missing.
Thus is is that Barnaby Weasley, Hufflepuff, is born.
Snape doesn’t give away anything more than a mild frown at another Weasley showing up on the class roster, but he does raise an eyebrow and inquire, “Hufflepuff?” after reading his name.
Barnaby (Fred, at the moment) turns red with the help of a Blushing Charm and looks hurt and defensive, which makes the Hufflepuffs, upset at the perceived insult to their House, accept him without question. Nobody ever asks either twin why he only shows up in Potions class; they get that it’s some long-con joke focused on Snape and they don’t interfere.
Barnaby is not quite as hopeless at Potions as Neville, but he is prone to the same wandering attention span as his brother, only more so. His potions regularly fail and occasionally explode, usually in a way that to Snape indicates carelessness with the ingredients and tells Fred or George something useful about the what happens when you do that.
The next year there are no new Weasley children, officially, but when Fred plops himself down next to George on the train and says “So what about a girl?” George knows exactly what he’s talking about.
They mix a hair-growing potion on the train, and have to hide it quickly when Draco Malfoy comes running into their compartment, frightened of the dementors.
George takes the hair potion and the shrinking potion and the pair of them use the Marauders’ Map to intercept Snape on his way to the Great Hall. Fred hides behind a pillar and casts a Duplicating Illusion Charm on himself and tries hard not to burst out laughing as George plays Nasturtium Weasley, little sister to Barry and Barnaby, who’s somehow managed to get lost on the way to the Great Hall.
Snape’s not the slightest bit pleased to be getting yet another absent-minded Weasley cousin, snarls, snaps something vaguely cutting, and leads her towards the Great Hall, intending to hand her over directly to Professor McGonagall; instead he runs into Fred and George (actually Fred and his charm double); Fred explained that they saw their cousin wandering off and went to go get her. Snape lectures the pair of them on wandering, accuses them of being up to no good, and stalks off to direct evil looks at Professor Lupin.
Which, luckily, takes up so much of his attention that he doesn’t pay attention to the Sorting. Fred and George decide the next morning, after careful consultation of multiple students’ class schedules, to put her in Hufflepuff along with Barnaby.
They strike it lucky again, in that first-year Potions only conflicts with Care of Magical Creatures, to which only one twin is going (they don’t see much point in both of them taking the same class, figuring that one of them knowing something is as good as both of them knowing it and they can teach each other more effectively than anyone else can teach them, an argument that failed to impress Professor McGonagall into letting them each out of half their classes back in first year); Hagrid won’t be expecting to see two of them.
Nasturtium Weasley, it develops, has quite a lot of bright red hair and a tendency to hyperfocus on ingredients or processes, leading to a lot of ruined potions when she keeps stirring too long or spends the whole class period shredding the shrivelfigs or gets lost examining the lobes of a dirigible plum leaf. Fred and George, taking turns being Nasturtium, are happy to spend the time just thinking through some interesting research they’ve been doing or contemplating a problem with their latest invention or just brainstorming new joke ideas until Snape appears, bellowing about melted cauldrons and the people who don’t even notice them because they’re too fascinated by the down on a downy mage-thistle.
But they’re being run just a bit ragged at it and decide that three is enough–until they wander past the Hospital Wing at just the right time to hear Snape bellowing apoplectically about Harry Potter, and Dumbledore’s more reasoned tones making light of the idea that Harry and his friends were in two places at once.
Fred and George look at each other and a light goes on.
They’ve heard about time-turners. They’ve also seen Hermione Granger run herself ragged studying textbooks for every subject available. They know how many subjects there are, and how many class periods in a week.
As one, they reach out and lightly smack each other on the head for not putting it together earlier.
Snape comes raging out the door just in time to see them and gives them detention. Fred and George scowl after him and turn and look at each other. And nod.
Fred “accidentally” bumps into Hermione when she’s on her way to McGonagall’s office, pretends to lose his balance, and falls hard to the floor. It gives him bruises, but sometimes sacrifices must be made for the successful theft of major, highly-regulated, top-secret magical artifacts. Hermione turns to help him, and George switches the time-turner with an elaborately crafted fake, a Confundus Charm and a Diversion Charm giving it the correct density of magical energy signature and ensuring that anyone who tries to use it will find an urgent reason to put it off. (George is super pleased with that one; it’s a time-turner, so quite naturally anyone who can use it has plenty of time to use it later.)
Next year is their sixth year, which brings enough of a drop in courses (there are definite benefits to getting only two OWLS each, though they doubt their mother would agree) that they only need to use the time-turner once, when Barry has Potions when Fred has Transfiguration and George has Herbology. They’re almost disappointed by this, until Fred gets a devastatingly diabolical grin on his face and says, “what if there were two of them?”
George’s face mirrors the grin in an instant, and he responds with his own suggestion. “Cousins.” A pause. “And they hate each other.”
And so come into being Gentian Weasley, younger sister of Barry, Barnaby, and Nasturtium Weasley, and her cousin from yet another branch of the Weasley family, Bilious Weasley the Second.
This time they give themselves some insurance, and make very good use of the time-turner, by charming Snape into seeing the new arrivals be Sorted. For a diversion they let Peeves the Poltergeist into the kitchens and assist him in creating havoc (testing out a potential product, tentatively named the Souper Swimming Pool, in the process); the amount of commotion takes three Professors to sort out, one of them Snape, and it’s surprisingly easy to hit the distracted Potions Master with the prototype of a Daydream Charm, highly modified to suit the occasion.
Once they’ve finished the time loop, they blast themselves with Aguamenti charms to make it look like they’ve just come out of the rain and sit down. Snape sees Weasley, Bilious and Weasley, Gentian be sorted into Gryffindor one right after another and summons himself a bottle of firewhiskey.
This is a mistake, as he has the keen and ignoble joy of being hungover for the worst Potions class he’s ever taught, including that one time when somebody (Potter) threw a firework into the Swelling Solution.
Gentian snickers when Snape reads Bilious’ name. Bilious calls Gentian “freckles.” Slytherin students from accross the room (the both of them are Gryffindors this time) look on in obvious amusement. Snape looks constipated. Their own supposed housemates eye them, looking confused, concerned, and generally bamboozled but none of them vocalize their curiosity.
Fred and George share a secret, gleeful smile, and escalate.
They spill things on each other: water, pigeon milk, stinksap. Gentian breaks a salamander egg on Bilious’ forehead; Bilious stabs Gentian with a knarl quill. They drop the wrong ingredients surreptitiously into each other’s potions. Bilious’ cauldron spews copious amounts of green smoke, gaining a lecture and losing five points for Gryffindor; his retaliation recreates Neville Longbottom’s disaster a few years prior and melts Gentian’s cauldron. Gentian shrieks at Bilious, Bilious dumps the whole jar of puffer-fish eggs over Gentian’s head, and Gentian launches herself at him, punching and clawing and screaming her head off.
Snape separates them with a wave of his wand and threatens them with a month’s worth of detention collecting bubotuber pus. Gentian says, “You can’t do that, I’ll tell McGonagall on you,” which neatly puts Snape off telling Professor McGonagall himself, because honestly, she probably will take issue with it. Bilious smirks loftily and sneers, “Baby. I like bubotuber pus. It smells like petrol.”
“How,” Snape asks suspiciously, “would a wizardborn young man like yourself know about petrol?” and Gentian (secretly Fred) hides a wince; their father’s particular fascination with Muggle things might be their undoing. But George recovers, saying proudly, “My dad’s an accountant.”
The Slytherins laugh. Fred catches the reference and Gentian says, “Oh, right, your dad’s the family Squib.”
Bilious grabs his cauldron and makes to empty it over her head, only to find that the contents are basically a solid baked into the cauldron’s bottom. Snape casts it away and tells them they’re more of a disaster than Neville Longbottom and deducts fifty points from Gryffindor, and they spend the walk out of the dungeons trying to convince their housemates that the points don’t actually matter that much.
Snape goes straight to McGonagall to complain, but refers to them as “Those two damned Weasleys,” and McGonagall nods and makes sympathetic faces and promises to speak to them. Fred and George get a detention with McGonagall at the same time as Gentian and Bilious have one with Snape, which makes them as happy as a time-turner can make two mischief-minded teenagers in possession thereof.
That year is a delight. They have a Triwizard Tournament to watch, a small multitude of visiting students from Beauxbatons and Durmstrang, many of them attractive, to interact with, and five alter egos with which to torment Professor Snape. Moreover, with the time-turner and the extra Potions classes, they’ve made significant progress on their product line and are turning a brisk business with the student body.
Snape learns quickly and the first time is also the last time he schedules Gentian and Bilious for a detention together. Fred and George take it in turns to run certain of their inventions past Flitwick and Sprout to gain back some of the points they lose in the first-year Potions class. By the time summer rolls around, Fred calculates that they’ve used the time-turner enough to have come of age and potentially erased the Trace on them.
They pay Mundungus Fletcher a galleon to come somewhere out-of-the-way with them and lend them his wand to cast a few spells. When no owls show up carrying Ministry warning letters, they head to Diagon Alley and celebrate by buying a storefront and the flat above it, and spend most of the summer there, fixing it up and getting things ready for a product launch next year. NEWTS, schmoots.
There’s of course that annoying business about Voldemort returning, and their mother decides the best way to keep them out of the Order’s business is to turn them into house-elves, but they come up with a few charms to do housework slowly by magic, and adjust the illusion spells, and put in just as much of an appearance as necessary.
Then September rolls around again, and their new Defense Against the Dark Arts teacher is even worse than Snape and Lockheart combined, and just like that, Barry, Barnaby, Nasturtium, Gentian, and Bilious all add themselves to Defense Against the Dark Arts classes.
This largely sucks, because the DADA classes are utterly useless this year, but Fred gets the idea of substituting their alter egos and eventually themselves with illusion charms (”She doesn’t actually teach, she’ll never notice”), which makes George laugh hysterically because they’ve progressed from attending classes multiple times as different people to using doppelgangers to avoid going to class at all, and the two tactics are completely at odds with each other. But they do it.
Umbridge doesn’t notice, and pretty soon the only class they show up for is the one where second-years Bilious and Gentian are forever hurling hateful looks, creative insults, badly-aimed spells, and improvised projectiles at each other.
Umbridge starts taking points from Gryffindor off at the first “blast-ended walnut” from Gentian and assigns the first detention at Bilious’ elaborately-detailed Muggle catapult. Fred and George add a line of Magical Model Muggle Major Munitions to the product array at the soon-to-be-hatched Weasleys’ Wizarding Wheezes, and make copious notes on how to use them as actual weaponry once Voldemort makes his appearance.
Fred writes “I must not fight in class” with Umbridge’s quill for six hours and then steals it. George listens to Fred’s description of the evening, takes one look at Fred’s hand, and breaks into Umbridge’s office and takes a generous crap on her desk. “Crude,” says Fred admiringly, “but deserved.”
The next time Barnaby has DADA, Fred goes as him in person and tests out a Skiving Snackbox. Throwing up on Umbridge is satisfying. He gets detention and writes “I will be more careful with how I am sick” some nine hundred times with a completely normal quill, charmed to write in red ink like a Muggle fountain pen, and mimes innocence when Umbridge expresses confusion at the lack of redness and swelling on his hand.
Gentian and Bilious get into a full-on wizards’ duel in their next DADA class, and aim so terribly that Umbridge gets hit more than they do. They both get detention, and Fred and George send illusions in their stead.
Next week they do it again, and Umbridge spends half the afternoon in the hospital wing, getting tentacles removed. Colin Creevey, confined to bed rest for a case of Exploding Hiccups, sneaks a picture and later trades it to the Weasley Twins for a Pygmy Puff, two Daydream Charms, and a promise to look into developing Extendable Eyes.
Umbridge goes to complain to McGonagall, who listens to the entire rant about a pair of students she’s never heard of with a reasonably straight face. Then she blandly tells Umbridge she’ll look into it, and turns back to her essay-marking.
McGonagall wanders down to the staff room the next morning and relates the whole conversation to the other teachers. Flitwick and Sprout are practically rolling on the floor by the time she finishes, but Snape is standing there looking Stupified; he makes the biggest miscalculation he’s made in years, and asks, “You mean they’re not real?”
McGonagall looks at him, calculates what all it would take for him to be asking that question, and promptly laughs herself sick.
Snape waits, looking like he might catch fire, until she recovers. “Yes, Severus. I have never heard of a Gentian Weasley, and the only Bilious Weasley I know is my age.”
Snape says, “There’s two Bilious Weas—who names these people?!”
“There’s one, Severus. I can assure you that there is no such person attending this school at this time.”
Snape thinks. “Barry Weasley? Barnaby Weasley? Nasturtium Weasley?”
McGonagall’s staring at him. “No.”
He grimaces, then tries, “I don’t suppose Ginny, Ronald, and their siblings are fictional?”
He closes his eyes. Opens them. “Fred and George.”
“Most assuredly real, Severus.”
“No, I meant–they did this. They’re responsible for this, aren’t they?”
“I would imagine so,” McGonagall says, a hint of a smile hovering about her lips.
He eyes her. “Shut up, Minerva.”
She claps a hand to her mouth to hide a giggle, and he turns and sweeps from the room.
As it turns out, he has Gentian and Bilious the next period.
Fred and George, blissfully unaware, are launching into their standard pretend fight—in this case, swordfighting with Transylvanian Lesser Pseudoporcupine quills—when Snape arrives at their table and claps a hand on their near shoulders. He’s smiling like a dragon.
They have a moment of sharp dismay, but it doesn’t last. They are the Weasley Twins, they’ve been fooling Snape for years with this prank, and they have money hidden in multiple places and the deed to a shop in Diagon Alley and all the official education they’ll ever need.
“Well done, Professor,” says George. “How’d you find out?”
“Professor McGonagall told me.” His smile was a thin, sharp blade.
“I’m afraid I did, Mr. Weasley,” says McGonagall from the doorway. “Although admittedly without knowing you were pranking Professor Snape as well as Professor Umbridge; I thought I was merely sharing a very amusing anecdote with the other teachers.”
They’re drawing curious looks, though fortunately Fred-as-Gentian’s cauldron is hissing like a teakettle and drowning out the conversation; Snape snaps at them to pay attention to their cauldrons before jerking his head at his office door.
Once they’re ensconced within what Fred once called the Snape Museum of Slimy Things, and Fred and George have undone the spells and potions that make them Bilious and Gentian, McGonagall turns to Snape and says, “I forbid you to expel them, Severus.”
He’s about to respond when Fred says, “Go ahead, expel us.”
That gets them two very surprised professors. George shrugs. “Everything’s ready to go. We’ve got a shop in Diagon Alley and enough stock to fill it and enough expertise for a lifetime of success.”
Snape frowns and asks, “Do I want to know what you’re planning to sell?”
George says, “No” at the same times as Fred says, “It’s a joke shop.”
McGonagall looks like she’s trying not to laugh. Snape looks like he’s swallowed a sea cucumber. He opens his mouth, closes it, and then says, “I would have never imagined an argument that could convince me not to try to expel you, but you’ve just provided it. I will not be assisting you in selling pranks to the student body of Hogwarts on a retail level.”
George says, “Actually, we’ve been doing it since the middle of last year.”
Snape turns to McGonagall. “I quit.”
“Hey, let Umbridge expel us,” Fred suggests. George snickers.
Snape looks at them, and then at McGonagall, and then back to the twins.
“No, you’re going to stay here,” Snape says, a look in his eyes that makes them wonder what all Umbridge has said to him. “You’re going to continue to be Gentian and Bilious—and Nasturtium and Barnaby and Barry.” He looks to McGonagall as if for confirmation, and George considers that both professors were young once, and were quite possibly as complete and utter hellions as him and Fred.
Snape smiles like a knife. “Give her hell.”
He’s never felt so much respect for a teacher before.
“Mr. Weasley?” Snape adds, almost as an afterthought, his eyes shifting from one to the other as if unsure which of them he’s addressing.
“Fifty points from Gryffindor.”
Fred and George smile at each other as they follow McGonagall into the hall.
They follow orders. Bilious and Gentian hit Umbridge with so many “accidental” hexes that she finally bans them from her classroom. Barnaby functions as a sort of a Patient Zero for Umbridge-itis. Barry uses his status as the quiet one to construct elaborate spells that have Umbridge’s classroom warping itself into odd shapes or growing spines out the walls or puffing up like a balloon and trapping her at the bottom. Nasturtium stands up in class one day and slams an epic poem about how teachers who don’t teach are useless and a sea sponge would do a better job of earning the salary.
Between them, they work to set up elaborate pranks and position Umbridge to catch the worst of it. After Dumbledore’s removal, Fred and George set off the best fireworks display Hogwarts has ever seen, and McGonagall gives Gryffindor one hundred points; Gentian and Bilius, usually the only ones still played in person by the Weasley twins, play Umbridge beautifully the next morning, fighting each other as usual and then turning ally, working together to attack her with flurries of squawking birds and flying, shitting replica nifflers.
When Umbridge twigs that they’re all working together she stands up in the middle of the Great Hall at dinner and demands that every Weasley in the place stand up.
Four Weasleys, all siblings, do so.
“Where are the rest of you?” she hisses to Ron, who looks clueless. Ginny cocks an eyebrow and looks to Fred and George speculatively. Umbridge turns to them and they smile like sharks.
Fred climbs up onto the table, George right on his heels. “Ladies and gentlemen, a performance by myself and my twin!”
George produces a potion, downs it, and becomes Gentian.
Fred narrates as George shifts between the various fictional cousins, ending by restoring his own appearance, putting on a pair of glasses, and becoming Barry. Snape slaps his face down into his hands. George finishes by announcing that these new appearance potions, and the fireworks, and a multitude of other products, would be available at 93 Diagon Alley, home to Weasleys’ Wizard Wheezes.
“Not so fast,” says Umbridge, holding out her wand. “The pair of you are going to be expelled—but first you are going to find out what happens to troublemakers in my school.”
“We’re not,” says George, “But let me tell you something: this is not, and will never be, your school.” He looks around at the students, at the teachers, at Snape and McGonagall standing a short distance away, and he and Fred wave their arms in a mirrored gesture to take in the whole student body, and they say, the pair of them together, “This is our school.”
The cheer from around them shakes the rafters.
Then they raise their wands and say, again in unison, “Accio brooms!”
The brooms make holes in the walls on their way in, and Fred and George mount them and soar up among the floating candles, and Fred has to cast a Sonorus Charm to make himself heard over the cheering.
“Weasley’s Wizarding Wheezes, number 93, Diagon Alley: Our new premises!”
And George waves to Peeves, who’s floating up there along with them, attracted by the promise of mayhem. “Give her hell from us.”
Peeves salutes, and Fred and George fly out the front door to freedom.
When they return to Hogwarts almost two years later, their time spent as the fake Weasleys serves all of Hogwarts well: the muggle munitions devices, some elaborate magical shielding, judiciously-applied daydream charms turned hallucinogenic means of luring the Death Eaters to shooting at false targets, and projectiles that created all manner of interesting effects, save the day for many people in the Battle of Hogwarts.
Fred never knows he came close to dying. George never knows he came close to losing his twin. They go back to Diagon Alley, afterwards, and as the world puts itself back together, they help people laugh.
