You woke up after about three hours of rest. You'd only noticed the note on top of you when you heard a crinkling noise as you flopped the sheets over to one side of the bed. You crumpled up Sans's note when you finished reading it, casually throwing it over your shoulder into the tornado of trash that seemed to be a permanent fixture in the corner of the room. Muffins sounded good before you completely ignored his request for you to not make yourself bone tired.

You gathered up all the dirty clothes that had accumulated over the last week and threw it into the wash before heading downstairs towards the kitchen. You blatantly refused to look at Papyrus because you knew exactly the kind of expression he would be wearing. Grabbing two muffins and a small bottle of orange juice, you waved at Papyrus as you left the house, signing you'd be home late.

The street in front of their house was positively bustling with activity. You weren't used to it being this busy and you faintly wondered what was going on, but you were determined to get back to training. You were so focused that you didn't even notice that you passed Sans until he grabbed you by the soul and dragged you into Grillby's. He spoke in a low voice to avoid being overheard.

"k, kid. i was absolutely serious about not working yourself to the bone. we don't know the limits of your magic, and if you push past those limits, the possibility of death is pretty high."

"And how are we supposed to explore my limitations without pushing boundaries, Sans?"

You challenged him with a look and he threw his hands up in a defensive manner.

"look, while i'm glad you're excited about this, you need to be supervised. i know all the telltale signs of magic exhaustion. you don't. k?"

You crossed your arms and resigned yourself to his conditions, on one condition of your own.

"Okay, fine. On one condition."

He looked up from the burger he had ordered.

"You have to train with me and teach me what you know. The blinking thing might apply to me, but we won't know until we try, right?"

He sighed and put down the burger, turning to look at you with a leveled glare before sticking out his hand. He was obviously not happy with that, but he seemed to give in regardless.

"we got a deal, then. just don't go back on your word."

He rubbed his forehead like he had a headache and sighed again.

"ya know, i kinda knew you'd be like this. determination, amiright?"

You grinned broadly at him, resolute in your decision to train until you dropped, knowing he'd stop you before it was too dangerous.

Over the course of the next few weeks, you learned to heal, make a shield, form bones into daggers mid-attack, form bone walls to defend yourself, and how to push those walls forward in the heat of battle. The ground in front of Sans's sentry station turned into a muddy slush during your training. The more you learned, the more intense Sans got, and in time it got to the point where he was no longer just dodging, but he was blinking all over what you had both come to call the battlefield. He was both brutal and gentle towards you, always giving you breaks and healing you when you didn't block in time, but absolutely not giving you any leeway when you two were fighting. You always had to wait for breaks to be healed, or do it yourself under a barrage of attacks and under a self-formed shield. No matter what you tried, you couldn't teleport like Sans, but you did discover that you had a sprinting ability that he'd never seen before you. You kept using it to the best of your ability so you could throw him off.

Sometimes Papyrus and Undyne would come to watch, once they caught on that the two of you were training every day. On those days, both of you didn't put in your full effort, in order to keep his secrets. It was like a silent pact. Undyne gave you tips on tactics, while Papyrus helped you with your stance. Day by day, your confidence grew, and eventually this weird bonding thing became the new normal for everyone in your friend circle. Even Alphys joined in every once in a while, though she did nothing but cheer.

The fighting got faster and faster until you had almost beaten Sans in his watered-down attacks. His real attacks still left you breathless and afraid. You hated being at the other end of his magic on the days that no one was watching. You understood why he wouldn't want anyone to know his real abilities, though, so you didn't want to push him any further. Instead, you suggested you train with Papyrus. Needless to say, Papyrus was thrilled.

"YES! SOME TRAINING WITH THE GREAT PAPYRUS WILL DO YOU SOME GOOD, FRIEND!"

Ah, you loved your big cinnamon roll friend. And just like that, the healing truly began.

Just like his brother, Papyrus would give you breaks and heal you, but you got wounded less and he eased up his attacks the moment you got hit. It was difficult just getting him to agree to continue once you got hurt. For once, you agreed with Undyne. If you were training, you needed a merciless opponent. It was odd, asking this gentle giant to be cruel towards you. But you had to. You eventually learned how to not show you'd gotten hit so he would keep going.

But, though you liked the training, the thing you looked forward to the most was getting home every night, making dinner, and curling up with Sans. You would give each other a recap of your day, or if you were too tired to talk, you shared your souls outside of your body. It was an intimate action that you had both made a casual part of your day, and the fact that you could do that with someone made you feel safer than you had before.

But you knew those scientists were up to something, somewhere out there, and that you had to be ready if they ever came back for you.