Sans followed Papy out of the kitchen when Frisk declared that she'd do the dishes, though not without glancing back at her as she started to hum that gentle tune. He recognized it as a song he hadn't heard in a very long time, but knew by heart. He was sure every monster parent did. It was warm and sweet, like a mother's embrace. He quirked another real grin before shuffling over to the sofa to take a seat with Papyrus who was killing a few minutes before heading to Undyne's with a replay episode of Cooking with a Killer Robot. He himself didn't care much for the show, but he could stand it since it was his baby bro's favorite show.

The pair watched in comfortable silence with the taller giving "oh"s and "ah"s at the cooking techniques used, obviously committing them to memory for later use.

And without realizing it, Sans' mind began to wonder in the silence, back to their talk of the surface. He was glad no one else remembered it, otherwise they might blame Frisk, like he once did, for reseting so many times, making all of them live through such horrible times over and over again. But she had been young back then, new and curious to these strange powers she had suddenly in this cave under an old mountain. And she'd eventually come around to reason, so that had been enough to prove to him that she wasn't evil, just mislead. And probably by that good-for-nothing flower.

All too soon, the short skeleton was drawn from his thoughts as Paps stood and bid farewell to everyone before heading off to his royal guard training. Sans watched and waved him off, sitting on the couch for a few more seconds before getting up as well and making his way up to his room. When he opened the door, he wasn't surprised to see it was still an incredible mess, his research from his night of agonizing how to extend Frisk's life still covering nearly every square inch of the room. He huffed a quiet sigh, reminding himself to go look through Alphys' notes later and maybe scrounge around for some of the former royal scientist's own human soul studies. It was an easy job to gather the clutter of papers, though it did take him a good minute to sort them out correctly. He'd been half asleep while writing most of these notes, so some of it was plain gibberish, but even just looking at what he had so far, he knew he was close. Maybe instead of a human soul, she needed a monster soul.... He jotted down that thought for later debate and shoved the stack of papers in his desk drawer.

The glitch soon made its way back to mind and Sans frowned. Very soon they would fight again, and he needed to be prepared. He needed to train. It had been a long time since he'd done anything remotely close to active training, but this threat... He couldn't ignore it.

His mind made up, Sans scribbled a quick note to Frisk and set it in front of his door before teleporting off into Snowdin's vast forest.

He looked around, making sure no one else was around before he set a timer on his phone and summoned a single gaster blaster, staring down the semi-sentient skull. Alright, so he knew what his worn-out, no sleep limit was, now he needed to figure out what his healthy limit was.

He closed his eyes and concentrated, focused and alert as he summoned another blaster, and then another, until eight fully formed blasters were circled around him and awaiting orders. He looked them all over for a moment, noticing the subtle, but very there differences between each blaster. Huh, he'd never really had time to notice any of that before. Shaking the thought away, he quickly teleport into the trees, hoping from limb to limb and fireing each blaster in succession at his imaginary enemy, coupled with bone barricades that crumbled into tiny, sharp, shards and flew at the fantasimal foe as well. Sans continued on like this for quite some time, switching from his high point in the trees to ground attacks and back over and over until he'd completely worn himself out.

His blasters faded off into whisps of blue magic as he fell back into the snow, breathing heavy, and pulled out his phone.

Thirty minutes. That was his limit for an all-out, no blows held back attack. He groaned and shoved his phone back into his pocket. Who knew being active was so much work?