A/N: I'm horrible at pranks, and I didn't want to go with any of the Australian muck up day staples because 1) they usually involve vandalism and 2) my cohort had a massive water fight on the back fields instead, so I'm borrowing from MIT's actual and rumoured hacks for this.
To Hermione's relief, Fred and George's plan doesn't involve anything that isn't wholly reversible. Her main concern when first agreeing to participate was that it would be something semi-permanent and would end up getting them in trouble with Arthur and Molly. Although the couple have always welcomed her, she has never quite been the honorary child that Harry is; she cannot forget how ready Molly was to cut her out of their lives after the Daily Prophet incident in her fourth year. The bond is stronger now that they have all lived through a war together, but part of her will always be aware that she needs the Weasleys more than they need her.
That was never the case with Ginny, who relied on Hermione as much as the older girl did on her. It no longer applies with Ron anymore; he was always quicker to walk away from their relationship than she was, but that has slowly started to change in the aftermath of their break up. And she is gradually realising that it might not be the case with the twins, either. But, still, she needs their family more than they, as a collective, need her.
Regardless, she is excited to see how the prank will turn out. On their slow walk to the lake and back, she and Fred tweaked the twins' plans to involve her as well. Her role is going to be as active and important as theirs, and the feeling of once again being instrumental to her friends exhilarates her.
Ever since they returned to the house, she has been doing her best to look innocuous, even as Fred and George slipped away to discuss the modified strategy. She is their secret weapon, their ace in the hole. If anyone suspects her ahead of time, it will all go down the drain. Still, it's hard to focus on her discussion with Arthur about Muggle political systems when her body is so full of nervous energy. Knowing that her partners in crime have changed, that it's Fred and George who share her secret rather than Harry and Ron, is a strange feeling; she's so used to hatching plans with the boys that it feels odd not to be able to send them conspiratorial smiles as they wait. Instead, George is the one who flashes her a quick thumbs-up from across the room as the twins return downstairs and integrate themselves back into conversation.
"Time for Quidditch, then?" Charlie finally asks, tying his hair up to keep it out of his eyes.
Teddy eagerly abandons the dragon figurines his adopted uncle bought him in favour of urging the others on. "Grandma, Grandpa, are you gonna play?"
Hermione hides a smirk. George has been casually dropping hints that Molly and Arthur might like to join in all morning, but they never expected Teddy to run with the idea as well.
"I don't play anymore," Arthur replies. "Molly, however…"
"Arthur," she cautions, but Hermione can see the interest stirring in her eyes.
It doesn't take long for the group to convince the couple to participate. Arthur, true to his word, refuses to play, but he does agree to umpire if Molly joins in. Within minutes, the extended Weasley family is shepherding itself out of the Burrow.
All except for Hermione, who offers to do the cleaning up, and Teddy, who would rather play with his figurines than watch specks zoom around in the sky.
"Teddy," Hermione says when everyone has gone, "I need you to be on lookout for me, okay? I'm going to be doing some very important things to set up a surprise for the others, but that means that no one else can find out about it until it's done. If you see someone coming back to the house, let me know, alright?"
"What things?" Teddy asks, his eyes wide as he stares up at her. While the adults have told him bits and pieces from their adventures at Hogwarts, he has never actually seen her get involved with anything sly, so the idea of her sneaking around is foreign to him.
"I'm helping the twins," she admits, knowing that alone will get him on board. The twins decided to start in on him young, letting him get involved with some of their smaller gags and encouraging him to do his own. If they have their way, he'll be the best prankster in the history of Hogwarts, melding years of experience and transgenerational knowledge with his burgeoning ability to change his looks at will.
It would, frankly, be kind of terrifying if he weren't so sweet.
Teddy nods vivaciously. "Alright!" he calls back as he runs to the door and starts playing with his toy dragons there.
She races through cleaning the dishes with a speed that would rival Molly's, determined to get through everything in time. The problem with the plan is that Fred and George can't leave the game without risking discovery, so most of the grunt work has to fall to her. The twins are aiming to distract everyone for as long as they can, but there's always the chance that someone will get injured and return to the house early.
As soon as the washing up is done, she sprints to the least frequented room and slowly but surely starts her task. Adrenaline pumps through her veins as her heart races, leaving her feeling more alive than she has in years. This, she realises, is the reason the twins love to pull pranks; they enjoy the laughter and the amusement of watching the others' reactions, sure, but they mostly do it for the rush.
As she hurries through the house, casting the spell over and over again until everything is in place, she feels herself falling in love with it too.
"I'm done," she finally tells Teddy after he watches her make the final changes to the living room. Crouching down, she adds, "We should go and watch the game now, partner. Can you keep this a secret for me? We don't want them to know it was us."
"I swear." He holds out the toys in his hands. "Do these too?"
"Are you sure? We can take it with us."
He nods emphatically. "I'm sure."
Smiling, she twirls her wand in a complicated loop, and they both watch the toy fly up to join the rest of the furnishings.