A/N: I own nothing except for Shirley Pines. The rest belongs to our Lord and savior, Alex.

This character comes from the theory that the baby Ma Pines was holding was not Shermy, and was instead a little sister. It makes sense since if the baby would be to young to be a grandfather of two 12 year olds by the time Gravity Falls goes on.

As kids, Stan and Ford had asked for robot arms and hockey lessons. Instead, their parents had given them a baby sister and a weekly boxing class. It wouldn't have been so bad, if it weren't for the fact that both of those things were ear-bleedingly loud and usually caused the twins much pain. Regardless, they still loved both.

"Look at that right hook! This kid is gonna be a champ when she grows up!" Stan announced, the 18 year old suddenly picking his 1 year old sister up and holding her out for his twin to see.

"Stanley, would you mind 'training' her somewhere else? I'm trying to read." Stanford huffed, though he did eventually lower his text just to look at the little one.

"What's the matter? You jelous of her mad skills? She got the tough gene like me." Stanley cooed, placing the baby on top of his brother's book. "Here, why don't you study something cute instead of your dumb nerd book?"

Frowning, Stanford looked down at the little ball of dough currently staring back up at him. Like the rest of the Pines siblings, she had curly, chocolate coloured hair. However, she had their mother's blue eyes, that would cross at her pinkish tinted nose whenever Ford would touch it with the back of his pencil. All in all, she seemed like every other baby out there, simply hitting at thin air just for the fun of it.

"Stanley, ma asked us to watch Shirley. Not teach her how to throw a punch." Stanford muttered sternly as he lifted the baby off of his book with a six-fingered hand and drew her to his chest to lay her down.

"Why not? It builds character!" Stanley retorted, quickly and somewhat roughly snagging the baby away from his brother.

"A one year old child does not need character!" Stanford gasped, trying to return to his book and gripping it a little tighter now.

"Geez, you sound just like Shermy on the phone last night." Stanley huffed, holding their little sister protectively with both arms as he spoke.

"Because Shermy is an adult with a child of his own on the way, Stanley." Stanford replied, rolling his eyes at the thought of his older brother. "He knows how to handle them."

"His kid isn't even born yet, and he's only seen old Shirls once when she was born." Stanley muttered, quietly returning to Shirley's playpen and setting her inside before getting inside with her.

"It'll never cease to amaze me how that thing can hold both of your weights." Stanford mumbled, only to gasp loudly when a baby block smacked him right in the face.

"Shut it. If this kid falls over then I want to be able to get to her ASAP." Stanley shouted over to his twin before returning his gaze back to his baby sister.

"Goodness, you're more of her mother than Ma is." The six-fingered twin mused, peering over his book to search the floor for where the block had landed.

"Hey, my mad parenting skills could be the thing that saves one of us in the near future." Stanley crooned proudly, poking the button nose of Shirley. "Ain't that right, kid?"

"No offense, Stan, but I highly doubt that your 'mad skills' will ever aid us." Ford laughed, finally setting down his book and going over to his siblings.

"It might! Who knows, Shermy could end up having super intelligent grandchildren who will come and stay with us and they might cause something totally crazy like a zombie apocalypse or a knomb fight or something like that."

"Stanley, I think you've been reading way to many comics instead of studying again." Stanford snickered with a slight roll of the eyes. "Children can't cause such anomalies to occur."

"Oh yeah? Well, check out this anomaly!" In a quick movement, Stanley suddenly picked Shirley up under her arms and held her up to Ford, whom she proceeded to left-hook with her tiny baby fist.

"Ow-"

"The amazing fighting baby! Heck, we could charge big money for people to watch this kid beat the crap out of you, and we'll call it 'Baby Fights'! You'd only get 1% of the profit though since you're the one getting beaten up." Stanley joked, lowering the little girl back down just as Stanford climb into the playpen despite his earlier concern about it.

"Absolutely not. No one would ever go for such a concept." Stanford teased, taking Shirley into his own arms and watching as the baby snuggled closer to him. "See? She likes me better anyhow."

"What are you talking about? She's just biding her time and gaining your trust." The other replied in an all to serious tone. "Plus she's a baby and isn't sure which brother she likes. She probably thinks that we're the same person or something."

Stanford rolled his eyes at the other before grabbing a nearby pillow and putting it behind his back so he could lay back a little with the baby girl still curled up comfortably on his chest. Following his lead, Stanley took Shirley's baby blanket and fashioned it into a make-shift pillow before doing the same. Smiles were all around between the three siblings, though the two older ones were silently hoping that their ma didn't do what she did last time and sneak up on them while they were in there and snap an embarrassing photo.