Undertale AU Sibling Oneshots

Underfell! Bros x Dating! Sister! Reader

(a bit of language, but hey, that's Underfell for ya)

Requested by the lovely BrightFire123!~

You sat at the bar at Grillby's, waiting for him to return to your side as he dealt with customers.
It was a bit busy today, not that you minded, you got to see more of your boyfriend doing what he loves the most. (My dirty mind: you mean doing the thing he loves the second most(imsorryplzdontkillme—))
Your brothers still didn't know however, you and Grillby didn't want them hounding you both with questions and threats about your safety.
You'd tell them eventually, just not now.
"You need anything?" Grillby asked once he was able to return to your side.
"Just your company~" you grinned, resting your chin on your palm. Grillby chuckled, glancing to the side when the door chime reached his ears.
"Seems we'll need to make plans later, dearest."
You groaned, already knowing it was Sans without even turning your head.
"Boss needs ya (Y/n)." Sans huffed as he took a seat at the bar, beginning to chug down the mustard Grillby wordlessly provided to him.
"Fine..." You sighed, getting up. "Just put my order on Sans' tab, Grillby!"
"Hey!"
"Will do, (Y/n)!"

You poked your head out of your room, glancing around for your brothers. No sign of them, so that was good.
You and Grillby wanted a night out, and of course you forgot about curfew.
Once daily rounds of the forest were over, Papyrus usually expected you to stay in the house in the late evenings, but tonight you'd have to sneak out.
Not exactly easy when your boss of a brother is basically your drill sergeant.
You don't even try to sneak down the stairs, you ignore them completely and teleport to the bottom.
Then you realize you can just teleport to Grillby's.
Duh.
Doing just that, you watch as Grillby jumps at your sudden appearance...
...with Sans and Papyrus right beside him.
"Ah shit..."

Ooooooh boy did you get an earful.
You don't even have ears!
Papyrus didn't let you leave the house for two weeks. Which meant you technically didn't have to work, but you also didn't get to see Grillby.
"(Y/n)!" Papyrus yelled, coming into the house with his usual 'im-better-than-you' ego.
"What?" You half snapped, still pissed off at him. A part of you wanted to add 'asshole' to the end of that, buy you figured you might be craving death with that one.
He ignored your half-hearted anger, and continued on.
"I have decided to let you see Grillby again, but on the condition that Sans and I know of your whereabouts should you go out again! I don't want you causing any unneeded mischief!"
And by that, he actually means "I worry about you and don't want you hurt."
Your gaze snapped to him. "You serious?"
"Very."
You legit rolled off the couch, jumping and bear-hugging him. "Thankyouthankyouthankyou!"
Before he could respond, you were out the door and running to Grillby's.
"How the hell are you runnin' so fast!? Your lazy ass doesn't exercise!"
"I've got a hot date with an even hotter boyfriend so F you, Sans!"