JSYK, I will want to make this tradition canon.
Fabian didn't make even the faintest sound. He just turned to face the other three and pressed his finger to his lips in the well-known symbol for "Could you lot please shut the hell up? I'm trying to catch a nargle here."
Alex giggled anyway, earning a pointed glare from little Charlie Weasley. The Annual Christmas Nargle Hunt was serious business, and while he had decided he liked these newcomers to the tradition, he was not going to be pleased if they once again failed to catch a single nargle just because some girls were giggling.
Gideon had taken point in this quest for nargles, with Fabian just behind at the head of the group of women and children. Arthur brought up the rear, just in case the nargles staged an ambush - because, as Gideon had informed his nephews, nargles are sneaky bastards. That had been right before Molly smacked him for using Language in front of The Children. Bill held Dorcas's hand, because she had claimed to be deathly afraid of nargles, while Alex carried Percy. The solemn three year old had taken an instant liking to Fabian's guest for some thus far unknown reason, and hadn't let go of her since the Nargle Hunt had begun.
Everyone knew where to find nargles, of course: in the mistletoe. Each round spray of it in the otherwise bare trees was eyed with great suspicion, and each tree was violently shaken in its turn (because, as Fabian informed them, if you shake them right any hidden nargles would come crashing right down). Now, though, they had spotted some remarkably low-hanging mistletoe. As the hunting party approached, Gideon slowed down and held his hand up to indicate a need to stop.
"Do you hear them?" he whispered as he turned around. Dorcas made a proper show of looking petrified as Bill held a little more tightly to her hand. He wasn't entirely sure he believed in nargles anymore, but it was hard not to get into the little edge of nervous anticipation brought on by the grand production that his uncles always made of the Hunt.
"Go shake the tree!" Arthur hissed from the back. "We'll be ready to get 'em!"
"No..." Gideon mused softly. "No, this time I'm going right for them."
"You can't!" Fabian gasped dramatically. "It's too dangerous!"
"Bollocks!" Gideon declared, still whispering. Molly was probably still going to smack him one for it when he got back to the house, though. "I will fight the beasts in their nest!"
Alex tried valiantly not to snicker at the dramatics, but it was really rather difficult with the Prewett boys both hamming it up the way they were. It was hard to reconcile this pair with the one she had seen tear up a battlefield. She liked them this way, when they looked for a bit like they didn't have a care in the world. She liked herself here, too, just carrying around a little kid and chasing imaginary beasts on the cold, sunny afternoon.
Gideon stepped forward to the mistletoe, breaking the quiet with a shout of "I'VE GOT YOU NOW, NARGLES!" as Dorcas played her part by shrieking in terror. She drew just enough attention to let Gideon pull the branch straight to his face and begin flailing around like a madman. Fabian of course jumped in immediately to try to save him from the nargle menace, faking a determined pull on the branch.
"Nooooooooo!" he shouted, flailing along with Gideon as the children charged forward to help with the rescue. Thank Merlin Charlie and Bill were there to save them, successfully pulling them away from the nargle-infested mistletoe. Dorcas and Alex and Arthur had all collapsed into laughter by this point, because really, how much could any human be expected to keep a straight face through?
Bill's belief in nargles was momentarily restored, and Charlie congratulated his uncles on their immense bravery despite failing (once again, for what had to be the thousandth year in a row) to catch even one tiny baby nargle. Alex, meanwhile, had plans for Fabian and the mistletoe as soon as the kids were out of view. Dorcas and Gideon, of course, weren't even waiting on the kids. It was understandable, though - one couldn't really deny a kiss to a man who'd take on nargles right in their own mistletoe.