He may be lazy, but don't underestimate his power
If you asked someone how strong Sans is, they'd laugh and say that lazy bones can't do anything without giving up. Frisk knows better. She knows better and she knows he's constantly holding back on the world. He may have 1 HP but that has never stopped her silly bones from anything.
Yeah, he's just as smart as her. Even when they get fully competitive he never goes 'all out'. It's just something that Frisk defines as a 'Sans thing' or...Timelines aftermath. But he had his moments. Moments in which he tried. And the skeleton can say it was all thanks to Frisk.
He'd see her struggle, he'd do something. A problem that she's stumped at? No biggie. Sans got it covered.
She is too tired to lift something?? No problem, his magic defies the laws of physics. Literally.
And Sans wasn't planning on stopping. Why? Because love is weird and it does this stuff of things to someone.
If you asked Papyru's opinion he'd simply say.
"MY BROTHER IS THE SECOND-BEST MONSTER! I DO BELIEVE THAT IF HE'D STOP BEING SO LAZY HE COULD TRAIN TO BECOME STRONG LIKE ME!"
Undyne would say.
"He's a bag of potatoes! He has only 1 HP! Didn't even know he had more magic in him than lifting stuff and teleporting before Frisk came!"
Alphys would say something about his wisdom being his strong suit, just like how she has no strength.
Toriel would compliment his humor.
Asgore would compliment his work in general.
But Chara, Frisk, and Asriel knew the extent of his power. Especially Frisk. She'd laugh to herself when she heard these descriptions of her lazy pile of bones.
"Yikes...they really can't pick up on stuff can they?" Chara would add as Asriel shudders.
They all remember the fights. They know how they used to fight.
They know the extent of Sans's power. There's a reason he's the Judge after all. But Frisk didn't mind, because together they were strong and together they would protect everyone they care for. And both of them were fine with it, even if sometimes people underestimated Sans by a lot.
Neither was better than the other in power. These two were equals. And they loved it.
Frisk was sick that day. But she was too stubborn to stay at home. So Sans was supposed to take care of her that day. It was his job as her boyfriend (if he may also add, future husband) so he didn't really mind. Frisk sniffled a few times, her head almost falling when she almost fell asleep on the bus. Thank god Sans had quick reflexes.
"you ok there, baby-bones??" Frisk sniffled and nodded, stifling poorly a yawn.
"I'll be fine...I caught a cold or something...It is that season after all." Sans smile slightly faltered in worry as Frisk sniffled once more then sneezed loudly. She blew her nose and Sans closed one of his sockets then looked away as she did. Gross...Humans have so many fluids in them...
"Alright, let's go or we'll be late." They walked out of the bus and they teleported to the school gate. They walked in and to Sans surprise, Luka and Louis seemed to be missing.
"Huh..." Frisk said, sniffling once more, then coughing. Sans sighed.
"don't talk for now, ok?" The girl nodded as she rested her head on Sans' shoulder.
And so classes went pretty smoothly. That was until they decide to go out to get some food after school. Sans and Frisk walked inside the McDonald's (because of course, Frisk would want that when she's sick, and who doesn't love a happy meal toy). So Frisk was waiting outside, leaning against the wall when a group of guys pulled in the parking lot. Two humans, two monsters. They looked pretty young but way older than Frisk for sure.
"Hey there doll, is something wrong??" Frisk sniffled and looked the guys up and down.
"Uhh no??" She asked, a bit confused at being approached.
"You look like you're sad...don't have enough money for a menu?? Want us to buy you something, princess??" Frisk looked around, hoping they weren't actually talking to her.
"Uhh...are you talking to me??" A guy chuckled.
"You're a funny little thing. What's your name, baby??" Frisk smirked.
"Nunya." A quirked a brow.
"Nunya??" Frisk's smirk grew.
"Nunya business. Fuck off." One of the guys frowns.
"It's rude to talk like that to adults, you know?" Frisk gasps.
"Ohhh my god! It's not like the fact adults approached me isn't shady enough. Go bother some chick at a strip club. I'm 16." The guys didn't budge. Frisk was beginning to slightly panic. She wasn't in the right state to fight these fuckers right now. The fact she's been out all day with a cold wasn't helping at all in terms of energy. Shit, she had to stall for time.
"Yeah yeah yeah, keep talking fuckers. Seriously do you have no shame??" The guys chuckled.
"Awww you're a feisty little thing." Frisk laughed warily and immediately bolted the other way. The guys on her tail.
Shit shit shit- She almost slipped once or twice as she ran. She jumped some garbage cans and boxes as she moved to run in alleyways between buildings. What a great way to exercise when you're sick huh??
It didn't take long for her to get cornered. She sniffled once more and looked behind her. The two monsters were now four and two humans. The humans were armed and the monsters had their magic out. Frisk may be strong but even she knew that she couldn't take them all on even if she was at her full power. Without the help that is. Apollo wasn't there either. She was screwed. She will get raped and--
"it's rude to corner a lady like that, you know that pal??" Frisk felt like she was going to cry in happiness.
"SANS!"
"What the hell?? Another kid??" Asked the human. The monsters seemed to chuckle.
"He's Gaster's kid. The one that has like 1HP. Sup kiddo? Here to save your lady friend?? Pfft--" Sans frowned, gritting his teeth in annoyance.
"scums like you disgust me." He said, taking a step forward.
"This kid is too lazy to do anything. Demeter go cut her a bit so he learns his lesson." Sans sockets went blank as one of the humans was now pinning Frisk down and was trying to cut her face.
"y o u f u c k e d u p" Sans said, his eyes flaring as everything went dark around them, a fight going on. Even if she was pinned down, she didn't seem distressed at all by the situation now that Sans was here.
"What the hell?" Asked one of the monsters as all of them and the humans had their souls drawn out in battle.
"W-What the?!" Sans eye flared with a blue clock inside of it and the attacks started. At first just bones, but then they became blasters.
"WHAT THE HELL ARE THOSE?!" Frisk chuckled as the guy on top of her let her go. The boy then did a round motion with his hand and the attacks started rewinding, hitting again. The humans and monsters were screaming as they tried to dodge. They failed miserably.
"GAH! IT'S THAT WHORE'S FAULT!!" Frisk scoffed, muttering 'puta' at the guy that just said that, and Sans's grin grew sinister.
"i'm done playing nice." Sans said snapping his fingers. Everything went dark as a voice came booming.
"you will now be judges for the LV and EXP that you have gathered and if you are worthy, i shall let you leave. if not? then there's a reason i'm the royal judge, you fools."
"H-He's the..."
"you shameless bastards. touching a god damn child with your filthy hands. the judging has commenced. you will suffer for all the EXP and LV you have. rot in hell, assholes." Multiple blasters surrounded the guys and in a few seconds, they all were vaporized, leaving nothing behind. Frisk's eyes glistened in awe as Sans rushed to her side.
"you ok?! fuck- i shouldn't have left you alone! did they do something? did they touch you?? god- i'll kill them again if I need to just--" Frisk cut him off by pressing her lips against his teeth.
"Just shut up...You lazy little shit..." She said, hugging him tightly. Sans snorted, patting her head.
"i know...i know...but come on, it's funny to see them underestimate my power." Frisk looked at him, unimpressed.
"You killed me, Chara and Flowey thousands of times. Do you hear your-fucking-self??" Sans hummed.
"can't really fuck myself but i appreciate the off- GAH!" Sans was silent with an elbow in his ribs, getting a wheeze out of him.
"A pervert and a moron. Let's just go home." Sans sighed and put his arm around her, smirking.
"understood." The two teleported away.