For the next few weeks, Sans trudged on with classes. Over and over, it seemed to be the same occurring classes, with reading and English and anything in between always ending with him passing out, yet somehow, someway, he always aces his studies in them. A few days of quirk training did, however, spice things enough for sans to not quit this. Well, that and the fact he could be arrested for his so called "crimes" but how is he one to blame?

It was seemingly another one of those days. Sans trudged to class 1-A for his concluding and favorite class of all time in this school. He haphazardly teleports to his desk, and tried to get some shut eye for the coming tests..until Aizawa did something unexpected. He was here in class early. It was awfully strange for him to be early, since he usually comes in when class starts on the dot. Aizawa was even awake for this, which made him question Aizawa in his head even more.

Aizawa sighs and looks to the class, looking over his notes. "Today's gonna be different today...we will have a special pair of guest coming in...one being the instructor, the other...." he smirks "a transfer."

Sans was a bit...well, put off by Aizawas smirk. The fact that usually Aizawa hates having more on his plate, plus the fact that he smirked without some sort of sadistic undertone to it made sans...on edge, strangely.

Kirishima, a spiky haired boy with teeth like a shark, spoke up first. "Aye! Teach! Mind telling us the new exchange student first?"

Aizawa sighs "well...she'll be coming around soon enough..." Aizawa says. "But....sans?"

Sans looked at him. "Eh...yeah, teach?" Sans says, nonchalantly.

Aizawa looks to him. "Might I ask...did anyone you used to know happen to...."

Sans froze, and Aizawas question was left both unfinished and unanswered to him. "Uh.....m-mind....telling me the....question again..?" Sans was frozen in fear. G-get it together, sans....maybe it could be...Tori! Or...Undyne.... sans relaxes a bit. He prays it's one of his friends...someone he trusts.

Then, the door slides open. And sans heart drops. It's the kid...but....she...was....she wasn't Chara for sure...

Sans gets up without Aizawas instruction. "K-kiddo...? Is that...you..?"

The kid froze too at the sight of sans. "S-s-sans...?" She smiles more "I...I missed you!" She says "it's me! Frisk!"

Sans smiles and the class just looks at the two with strange looks. "Eh...shes your...girlfriend or something?" Denki, the electric pickachu lookalike says.

"Eh.....NO!" Sans says, hitting his head with a light but noticeable thump. "She's...a friend!" He says "we knew eachother way back! Right pal?" He smiles "or are you the same....numbskull I remember?" Sans giggled.

Frisk giggles, before a red aura envelopes her, and another figure appeared behind her.

"Ha Ha....nice joke, you smiley trashbag."

Sans froze at the other voice, and his eyesockets hallowed out a bit. It's her as well....Chara.

Frisk froze at her voice, and Chara giggles. "Ah, so we finally meet at last, eh...? All three of us..again." She says.

Sans smiles more with his darkened hallowed eyesockets. "Yeah...same for you, you demon..." he says, looking aggressive.

"Y-you...okay....Sans...?" Izuku says from the back.

"I...I am...well...it all depends...on what that bitch has to..." sans says, before Aizawa cuts him off.

"Seems you two have a history...? Moreover with...well, Chara here? As frisk specifies, her quirk was a manifestation of something...Chara as you put it...as frisk shows signs of pacifism and calmness, Chara exhibits the opposite...yet still retains enough sanity to not outright attack....and the story you gave us, about your murderer?" Aizawa says "we lined up the killer...Chara, explain yourself."

The class...was awestruck. Before them stood a literal entity of carnage and genocide...and everyone's heard the story of sans friends and family being murdered...and how sans sees frisk, it seems sans loves her in some way, but...not Chara.

Sans gulps and nods. "Chara....she took everything away...I won't say how...but...let's say I tried to stop her...it didn't end up well..." he says.

Then, Izuku froze. He remembers a scar on Sans chest whenever they hit the showers. "Y-you...your scar..."

Sans sighs "a gift courtesy of the demon you see before you..."

Chara giggles "aw, don't be so sad! It was just a scar! It makes you Oooooh so tough!" She smiles "but...eh...I will say our previous tangoes have left me bored...this place though..I see a place of oh so many possibilities! I made a deal with Frisky here!" She floats down "we play nice if we can keep this world the way it is...we don't play rough if it doesn't get boring...and this place ceases to amaze me!" She smiles.

Sans froze. "Oh? So you mean to tell me killing my family and friends over and over again wasn't eno-" sans froze and looked at the class. "Shit...."

"S-sans...." Momo spoke up. "What do you mean..."

AllMight suddenly slides in the door, making everyone jump. "I AM HERE....in a very tense situation...? Whose...oh the transfers! Welcome! Play nice! Remember the-"

Chara smiles "of course! Play nice..." she looks playfully at frisk and sans "that was the deal....I mean...right, sans..?"

Sans just looked down with hallow eyes. "Y-yeah...I...I just..." he sighs and teleports to his desk, putting his hood on. For once, a face that haunts everyone, including Bakugo, was of sans...not smiling.

Aizawa sighs. "Class...sans will explain himself at a later time...for now...let him cool off...frisk, you may comfort him...while...Chara. Distance yourself. You already know what you did."

Chara grunts but obliges, leaving frisk to slowly walk over to sans, who was frowning. She sits down by him and takes his hand. "Hey...bud..." she says "I....I had to tell them...this was a new world..and they caught us..and.." she actually tears up. "I'm so sorry...none of this would have happened..if.."

Sans looks at frisk but sighs "no...it's okay, kiddo...it wasn't your fault..you...it's..." sans sighs and hugs her himself. "It'll be okay..."

AllMight sighs and looks at the class. "Students...put on your hero outfits in a few minutes...today...we'll be doing special training with me...but for now...let sans...process this...it's a lot for him to take in..." AllMight actually sits down and sighs with Aizawa. "So..." he whispers. "Sans wasn't of this world..."

Aizawa sighs "Frisk...the nicer one...confessed everything...her quirk..or power...whatever it is...allows her to reset timelines...or return to a point before her death..." he says. "While Chara can kill things in one hit, it seems...she can also output damage she causes...so she can cause a small cut or a nasty bloody death..." he says. "And..sans will soon reveal his past to the rest..:it was a hell of a thing to hear from the pair...and it explains everything...if sans gives a similar story...well...." he sighs "guess scientist can rejoice in that multiverse theory..."

The class quietly watch sans and Frisk weep silently as they held one another, before Chara just sighs. "Alright...enough with the-"

Sans summons a gaster balster and aims it at Chara "don't you fucking dare..."

Chara smiles "okay, big man...okay.." she backs off. She didn't have a physical form, but already knew that his blasters would vaporize her spirit based on her LV.

For some time....it was silent. Sans and frisk comforted one another. Then....frisk and sans gets up and sighs.

"....we can begin your lessons, AllMight..." sans says solemnly.

(Sorry if this felt a bit rushed but I felt o should have brung in frisk and Chara sooner or later since they're intergral to the lore of sans. Plus I'm sure your all bored of stories of just sans and nothing else. We need a bit of spice in our lives every once in a while, right?)