It wasn't that great of a day.

The clouds were out, covering the afternoon sun, the fall cold was creeping in, and the grass outside was wet with the remnants of the morning's drizzle. That wasn't the kind of weather that got the joints oiled for some outdoor exercise.

Not that Sans was ever up for a jog in the first place or any place really.

Rain or shine, he was perfectly fine with sitting in his room, snug in his jacket, and watching Frisk play around with a tower of blocks.

The kid's brow was knit tightly with concentration as they went on their tippy toes to put another colorful block at the top of their creation. With an incredibly steady hand, Frisk slid the block over the topmost piece of the tower but their toes gave out before they could push it all the way to safety.

Crying out as they stumbled, Frisk watched the precariously balanced block slip over the edge and fall, destabilizing the rest of the building. It all tipped to the side, falling apart, and then just froze completely mid-air.

Gaping in awe at the defiance of physics, Frisk noticed that a blue glow had surrounded the blocks. Turning to the bed where Sans was lounging, they found the skeleton laying back resting his skull on his crossed arms. One of his eye sockets was glowing the same icy blue.

"Couldn't let something like that go to waste, kid," Sans grinned, watching Frisk rush over to the side of the bed with awe in their eyes. The big excited smile stretched across their face threatened to make Sans blush. "Eh, it's no problem."

Pointing at the glowing blocks, Frisk moved their finger up and down. They were tipping their head to the side with curiosity now.

"Yeah, I can move them around," Sans waved his arm and some of the blocks rose up to the ceiling. Frisk clapped excitedly as Sans let them spin and twirl around the air. "You've seen Papyrus do this, right? Remember? It's his special blue attack. Eh, it's like his blue attack." Sans shrugged.

"I can do it too but Papyrus makes better use of it."

Gently, he placed all of the blocks back to where they were before. Even the highest block was placed right back in its perilous spot. Frisk took a step towards their blocks and it all tumbled down at their feet, making them jump back in surprise.

A long pause followed until the blue light returned to the blocks and reverted them back to their places in the tower.

"Hehehe, just joking around with ya." Sans laughed, deciding to go back to just laying around. Papyrus and Toriel were probably almost done with the pasta pie dinner and it didn't look like Frisk was going to let him take a five minute nap.

Losing interest in their blocks, Frisk went over to tug on Sans' sleeve. They pointed over to a bunch of books and Sans, thinking nothing of it, made them float. Clapping again, Frisk pointed over to the dresser covered in framed photos and knick knacks.

Easily lifting the piece of furniture with his magic, he levitated it in an arc over the bed. Frisk climbed up, sitting next to the skeleton for a better look.

With a flick of his wrist, Sans turned the dresser upside down. The stuff on top of it was kept stuck to where they were as the dresser's bottom came to rest on the ceiling.

Frisk's mouth turned into an O shape, letting out a silent "oooooh." Eagerly, Frisk pointed at themselves.

"Easy peasy. I could do that in my sleep," Sans said, falling back limp on the bed. "I'll do just that."

Sans closed his eye sockets, hearing Frisk shout with glee as he levitated them off the bed.

The kid had done this before when they had fought Papyrus but they didn't have time to have fun with it. With Frisk flailing their arms around, Sans only had to slightly nudge them with his powers to make it feel like they were swimming through the air.

In all honestly, Sans could levitate them safely through the air while he was half asleep. Even if Sans could fall asleep next to a burning firework factory, children's laughter was especially easy to relax around.

While Frisk flipped themselves and tried to walk across the ceiling, Sans let his mind stray.

Man, he was real good at this. With hardly any recent practice too. In fact, when was the last time he had used his magic?

Frisk giggled again and the memory of barely escaping the point of a knife came rushing back to Sans.

He had jumped back and that white dusted knife cut the edge of his jacket. But that bloodthirsty little freak wasn't done. With that disturbingly guiltless smile plastered across their face, they lunged at Sans again. Fear and blunt fury pounded in Sans' chest and he did what he did best; smash the freak into a wall.

Sans thrust his hand down, slicing it through the air, sending the freak flying.

Frisk screamed, waking Sans up.

The skeleton was back in the current timeline; the one where that freak didn't exist.

This wasn't Asgore's castle, they were above ground, and Frisk was about to get their face smashed open on the corner of the bed's frame.

Sitting up with a start, Sans stopped Frisk just before their tiny noggin hit the sharp wooden corner and moved them a few inches over to the safety of the mattress.

Clutching bunches of his jacket, Sans waited for Frisk to pull themselves up before he let himself breathe. The kid rubbed his nose and a sharp jolt of panic hit the skeleton until he realized that Frisk was just taking care of a nervous itch. Sans wasn't too late.

Though shaken by their sudden fall, Frisk was more worried about how Sans had gone completely silent. The glow in his left eye socket had dimmed a little but something else in the skeleton's expression made the child anxious.

"Hehe…" Sans tried to lighten the mood, snuffing his magic out. "Whoops."

The dresser that had been stuck to the ceiling came crashing down, nearly cracking the floor open.

"Double whoops," Sans made an attempt at a smile but combined with the sheen of sweat on his brow, it only made him look more upset. "Forgot about that thing. Oh well." Sans shrugged. "I told you, right? Papyrus makes better use of it than I do."

As if on cue, Papyrus opened the door and poked his head into the room. Saying absolutely nothing at the wooden disaster stuck upside down on the carpet, Papyrus blinked, backed out of the room, closed the door, opened it again, and walked in.

By then, Sans had used his magic to place the dresser back where it was, albeit with a few ugly cracks.

"Wow, I just had the worst day dream! Nyeh heh heh!" Papyrus exclaimed, laughing merrily. "The pasta pie is all done thanks to Master Chef Papyrus. With a little help from Toriel of course!" Papyrus continued. "Wash your hands and come down to feast!" Finishing his announcement, Papyrus headed back downstairs, leaving Frisk and Sans alone again.

Stuffing his hands into his pockets, Sans slid his legs over to dangle them over the edge of the bed. It was hard to face the kid right now.

"I guess I don't need to ask you to not say anything about this hehe…" Sans trailed off, feeling a little more than dumb at that moment. "…Sorry."

Something bumped into Sans' back hard and arms wrapped around his shoulders in a tight hug. Frisk nuzzled the back of his skull and that was the best and fastest answer he could have possibly gotten.

Sheepishly smiling for real this time, Sans got off of the bed with Frisk still clinging to his back.

"You're going to make me give you a piggyback?" Sans asked, turning his head to look at their beaming face. "Well, just this once."

Taking a step forward, Sans pretended to slip and fell back against the bed, smushing some more giggles out of the kid before getting back up and carrying them down to the kitchen.

Notes:

I would like to think that after a couple of runs, Sans would begin to see the differences between what Frisk does and what the person (possibly you) pulling their strings does.

That's really all I have to say? This was a lot shorter than my other fic but it feels more to the point. That's an accomplishment, I feel.

Another quick note, Electrified-Lizard's art work here is super cute and inspired me to write this (thought it took a different turn): post/130854216412/sans-using-his-powers-to-play-w-frisk-bonus

Oh and it's super late/early at the time of posting it so I have a weird paranoid feeling that I made a huge mistake somewhere but my tired eyes can't see it. Hopefully I'm wrong but it not, it will be fixed later!