Updated trigger warning list at the beginning of Chapter 1. Please read that; they apply for the whole story. Be safe and take care!

"The most important thing to remember about polar coordinates, really, is-"

"Take that!"

Sans was cut off by a yell from across the house, followed by shouting and raucous laughter. The afternoon had been going fine at first, but then Papyrus decided to get out the board games, and the two teenagers had barely managed to get out a full sentence in the last ten minutes. Grillby spun around in the desk chair and Sans smashed his face into the carpet.

"Ugh, we're not getting anywhere. I can't believe Frisk is so intense about Scrabble." The floor muffled Sans's words a bit, but Grillby caught most of them. He scrutinized his paper carefully and was surprised at the ease with which he could now interpret the numbers and symbols adorning the page.

"You know, I-"

"Aha! Your use of a Q is no match for my double word score!"

Despite the interruption, Grillby chuckled. "Sounds like Papyrus is pretty excited, too."

Sans sighed, lifting his face from the ground. "Yeah, he tends to feed off of others' enthusiasm. He's like an adorable parasite." The two friends sat for a bit, quietly listening to the shrieks floating down the hallway. Grillby checked his phone.

"Well, we've been at it for almost two hours, and," he paused as a particularly loud cry came from Mike, "and I actually feel pretty confident for tomorrow. A little break wouldn't hurt."

"I like the way you think." Sans stood and stretched his back. "Lucky for us, I know just what we should do."

With that, he started out the room, heading toward the commotion. Grillby followed, and they arrived just in time to see Frisk performing a very creative victory dance… with Papyrus's scarf wrapped bandana-style around their head and Mike's arm cradled in their own. The latter sat there, looking at his stump dejectedly. Papyrus ran up to his brother as he walked into the room.

"Sans! Frisk beat us in Scrabble, which means they are very good and were very determined to win because usually I am the very best at Scrabble. Did you know that there are words that have a Q but no U? Mike told us about betting so we all betted something that the winner got to have for two whole minutes. I betted my scarf and Mike betted his arm. Frisk betted their stick but since they won they get to keep their stick." Frisk proudly patted the stick in their back pocket while in the middle of a complicated version of the macarena.

Sans jumped in when his brother paused to take a breath. "Wow Frisk, you're pretty smart." The kid beamed at him before continuing their dance, throwing in some leaps and dramatic head tosses. "And you guys placed bets? On Scrabble?" The three nodded enthusiastically. "That's cool, I guess, as long as everyone gets their stuff back before they go home."

Frisk dropped to their knees, holding Mike's arm like a guitar and strumming vigorously. Grillby clapped politely.

Mike's watch beeped. "Okay Frisk, it's been two minutes. Gimme my arm back."

Frisk strummed three more times in rapid succession before popping up and gently handing the prosthetic back to their friend, then spinning on their heel and throwing the scarf at Papyrus, who happily wrapped it back around his neck.

"Alright," began Sans, rubbing his hands together, "Grillby and I are tired of doing math. Can we play with you guys for a little bit?" Mike nodded as he put his arm back into place and Frisk gave a thumbs up. Papyrus gasped.

"Wowie! Sans, Sans, can we build a fort?"

The older Roman grinned and gestured to the pile of blankets he had conveniently placed in the corner the night before.

"Way ahead of you, bro."

The five of them built the fort quickly, and soon enough there wasn't a piece of furniture that didn't have a blanket draped across it. Sans crawled inside, a pillow under each arm. He kept one for himself and threw the other at Grillby, who smoothly caught it with his face. Frisk, Mike, and Papyrus were already reclined against their own pillows and were sorting through the Roman family's mediocre DVD collection while the older two got themselves comfortable, Sans quizzing Grillby on formulas he would need for the test tomorrow. They both looked up at a sudden sharp intake of breath.

"What do you mean you've never seen Harry Potter?!" Papyrus and Mike were looking at Frisk, shock written on both of their faces. Frisk shrugged and opened their mouth, but the other two were already on the move. Mike began frantically searching through the case for the first movie while Papyrus crawled over to his brother.

"Sans, can you please make us popcorn? Please please please?"

Sans smiled and ruffled Papyrus's hair. "Of course, bud. You know how to start the movie?"

Papyrus nodded before eagerly turning back to aid in the search for the film.

"I think we've got some Gatorade in the fridge. How'd you feel about helping me carry all the snacks, Grillbz?"

The teens ducked out of the fort and made their way to the kitchen. Sans grabbed a bag of popcorn from a cabinet and stuck it in the microwave, directing Grillby to the fridge.

"There should be some red ones on the left side, top shelf."

Grillby grabbed five bottles and set them on the counter. They stood for a few moments, listening to the popcorn popping and the Harry Potter theme song playing from the television.

"Thanks for being chill about spending our break fort-building. If you want we can leave the popcorn with them and go back to working on the review problems."

Grillby thought about the offer and sighed. "As much I love cinematic misinterpretations of beloved literary characters, we should probably finish the review."

"Sounds good to me," Sans said as he grabbed two bowls and dumped some popcorn in each. They brought the food and drinks into the living room and left some with the kids before heading back down to Sans's room with their own refreshments. The teens settled back into their previous spaces.

Another hour passed by without Sans and Grillby noticing. In between working on problems they entertained themselves by throwing popcorn at each other and shooting the breeze. It was… nice. It was fun. It was such a nice, fun environment that Sans was put completely off his guard. He didn't even realize Gaster was home until he entered the bedroom.

Gaster stepped in just as Sans caught a piece of popcorn in his mouth. When he saw his father standing in the doorway, white hot fear bloomed in his stomach. Sans desperately grabbed at the snack bowl, but it was too late to hide it.

With a pleasant smile on his face, Gaster greeted his son and friend. "Hello Sans, and hello to you too. I don't believe we've met?"

Grillby stood quickly and stuck out his hand, looking flustered at the unexpected arrival. "Mr. Roman, hi. I'm Sean, Sean Bradigan, Sans's friend from school." The two shook hands, the amiable look never leaving Gaster's face. Sans scrambled up from the floor and wiped his hands on his pants, trying to control his breathing.

"I'm terribly sorry, but I didn't realize Sans would be having a guest. I only picked up enough takeout for three."

"Oh, uh, that's okay," said Grillby, "I wasn't expecting to eat here anyway. Um, my car's at the school…"

"I can give you a ride," Sans said quickly, jumping at the chance to avoid his father for a little longer. He's gonna be so pissed…

Grillby grabbed his bag and silently followed Sans out to the car, waving goodbye to Papyrus and his friends.

Once he was behind the wheel and out of sight of his father, Sans let out a deep sigh. Grillby looked at him in concern.

"Sans… are you okay?"

The shorter teen refused to shift his gaze from the front window. "Yeah, Grillby, I'm fine."

"Well, you don't seem fine. You kinda freaked out when your dad came home."

Sans clenched his jaw. "Did I? Because I don't recall that."

"Sans, seriously. You… you looked scared. What's going on?"

"You know what, Sean? Even if I weren't okay, which I am, it really wouldn't be any of your business, now would it? You barely know me, so stay in your own damn lane."

Grillby looked away, hurt. Neither said anything for the rest of the ride.

By the time Sans got home, both Frisk and Mike had left and Papyrus was finishing the movie by himself. He was so absorbed in the thrills of Gryffindor winning the house cup that he took no notice of his brother's entrance. Gaster, however, did. He looked coolly at his eldest son, the warm facade from earlier gone. He strode over to the stairs, walking down without a backward glance. He knew Sans would follow.

The teen carefully stepped down to the basement, every excuse he had come up with in the car dying on his lips.

"What," began Gaster, "do you think you were doing?"

"Look, I know I was eating outside of the allotted time, but I'll have less grain for dinner to compensate! It was just some popcorn, it's not a big deal!"

"Not a big deal?! Sans, your idiotic, reckless behavior could jeopardize the entire project!"

"It was just a bit of popcorn!"

Slap.

Sans reeled from the impact, cheek stinging.

"How stupid can you possibly be?" hissed Gaster. "Did you not hear anything I said? Have you not listened to me at all in the three years we've been conducting this?"

Lowering his gaze to the floor, Sans clenched his fists.

Gaster's face softened. "Sans, I love you and your brother. You're both so precious to me, and I only want what's best for you."

Sans looked up sharply. "You electrocuted me!"

"And you were fine!" cried Gaster. "You had no burns, no lasting side effects! Sans, I have given you the greatest gift a father could give. This is the closest humanity has ever come to any form of comprehensive immunity, and you are the first to receive it!"

The younger Roman closed his eyes, willing the tears to recede. "Have you ever thought that maybe I don't want this?"

"Sans, my son, you must remember why we're doing this, why I need you. If you don't go through with the project there will hundreds of thousands more unnecessary deaths, deaths that you could have prevented. Do you want their blood on your hands?"

Gaster had given some variation of this speech countless times. As much as Sans didn't want to admit it, as much as he wanted to scream and leave and just give up, his father was right. This wasn't about him; the headaches and pain were nothing compared to the overwhelming benefits of the serum.

"Okay," he whispered, "I'm sorry. I won't go off my meal plan again."

"That's my boy. I love you, Sans."