New cat Stan au where the only difference is hes got size-changing abilities.
Ford about to make a Bad Choice? No longer! Big Nikola is on the case!
Lose something under the couch? No need to worry! Tiny Nikola has you covered!
Especially hilarious if Ford doesn't even realize he can do it at first
Finally. The perfect au for fluff and bullying abilities. Tiny Nikola can fit in the palm of Fords hand, itty bitty and perfectly pocket sized. Big Nikola can perfectly crush Ford under him and lick the back of his head with his sandpaper tongue, easily pinning Ford and absorbing his struggles with his fluff.
Ford has a rough day? Mega Nikola for him to flop on like a giant pillow. Full body vibrations like the worlds best massage bed. Stan wants to be a more precise nuisance? Here comes tiny Nikola to sit under Ford's hand while he works and leave tiny paw prints in ink across his things.
(also i imagine tiny Nikola is 'helping' get things by pushing them further away, then staring at whoever lost the item until they pull out the goods (cat treats))
But also yes Ford not realizing his cat can change size is perfect. Stan has no idea what his limit it but its been very handy getting around from place to place. Usually just makes himself dog sized to normal cat sized, too terrified to go smaller and aware enough to know a giant cat would get too much attention. Stays regular cat sized at first, varying to larger and smaller cat sizes depending on his needs (pinning Ford to bed, squeezing in through windows, etc) and Ford sees none of this. A cat is a cat and its cat sized, the weight is just all in his head! Feels heavy when he wants to get up do to 'cat sitting on me' logic and no other reason. Lighter when Nikola wants to get anywhere due to 'cats don't actually weigh that much' reasoning.
Right up until Ford gets into some kind of dangerous Shenanigan, or is about to make a decision Stan-
No wait. Better idea.
Fiddleford ALSO doesn't notice, due to Stan staying in a generally similar size range and not wanting to smash Fords things by going too big, and the first time either of them discover Stan has this power is in the caves when the light goes out. One second they're in the dark, next they have a light, and Stan panic grows big and now both Fords are pinned under a giant cat stuck in a tunnel. Fiddleford is smothered in fluff and Ford has the unfortunate knowledge of what being crushed into a cats forehead feels like as Nikola's paws squish him into his cats face while Nikola chitters and his eyes are the barest slits.
Its very soft except Nikola's claws are right by his head and digging into his back a little and he is being crushed. Fiddleford is also sputtering somewhere, and its a miracle the light hasn't gone out a second time.
Takes them ages to calm Stan down enough to get him to shrink, and both think it has something to do with the little rock creatures until Stan, realizing the cats out of the bag (heh), decides to use his power as intended.
Being the ultimate botherer.
Gets just small enough to exit the tunnel (shoving his face into Fords side the whole time) then decides its time to stop walking forever and makes himself kitten sized and climbs into Fords hair, where he lives now. Then when the Hide Behind comes around Stan is dragging Ford by his backpack out of the camp while Fiddleford scrambles to follow, then back to small when theyre in the space ship.
Then mega Nikola to the rescue, smashing the Gremlobin out of the sky and scruffing FIddleford. Carries them all home and its too late people know he cares so he might as well flop on top of Fiddleford and purr while he's here.
Now its size changing cat hours. Fords stays up too late and gets dragged from his desk to his bed and can't get up. Fiddleford finds the smallest cat raiding the fridge, blissed out because this one slice of turkey is now ten times his size. Neither of them can get to the lab because Stan is blocking the hallway, dead asleep. Teeny tiny cat Stan is the perfect size to wiggle into the places he's not supposed to be, and Ford opens up drawers to find him so many times its not even funny.
Carla? Now subject to Stan putting a paw in her face whenever he thinks she's siding with Fiddleford too much.
Carnival? Now has a new attraction in Giant Sticky Panicked Cat. Potential rats? He is so big they are flying into the sunset with every whack.
Bord? Stan has a gross stomach ache where he's laying across the thing possessing his brother, and Bill's throwing a tantrum as he tries to wiggle out from underneath a giant cat. Bill Wins scenario? Now there's a Bill sized cat here to battle him giant mecha style. Ford had to make a size changing collar and now he's clinging to it screaming while Bill and Stan go at it.
The size changing does not apply when he's human shaped, but would be really funny if Stan got stuck at whatever size he was equivalent when the curse breaks. Normal cat = normal Stan. Big cat = big stan, tiny cat = tiny stan, etc. They learn this by Tiny Nikola trying to run away after Crime then all of them looking at Tiny Stan as he screams in Fords arms. Stan has to go back to basic cat size settings (or go a little bigger) if he wants to be human sized.