Do you know what the butterfly effect is? Well then search it up becuase he author is too lazy to explain.

Time is like dominos. One reaction triggers another reaction and then the dominos split, making another chain of different reactions. Now imagine the different splits in the dominos paths are different timelines and something as small as a flick of the finger causes that reaction.

The one who causes the flick is Frisk... but... another entirely different entity builds the dominos. One... behind space and time.

You and your big brain probably instantly thought ☝︎✌︎💧︎❄︎☜︎☼︎but no... its not them. He is still shattered upon space and time, he simple doesn't have the body to build it.
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So who? Is it a monster? Or a humans? Is it God or just a quirk? Is it a random person on the Internet who's making us into a crossover?! Well, yes but no. I am just the storyteller I didn't create this timeline.

This is what Papyrus was thinking at the green engulfed his soul. Of course, he couldn't hear me, but he gets the point.

Thought were swirling as his once grey soul was staining a beautiful light green. He felt everyone in the worlds pain and suffering. Imagine living feeling this pain all of the time. Have more respect for the green soul.

The more negativity... the more the soul wanted to tear itself apart. He was also smarter, aware of what role Frisk plays. No wonder they were trying to hide it, it must of been a heavy burden.

Everything was so clear.

Back at the hospital

Everyone from class 1-A except for a couple of people were there. They were all comforting Sans' brother even though they didn't know him. Even though his brothers... accident... he seemed in a good mood. He had a smile on his face, telling skeleton puns and acted like it never happened.

On the middle of a very SANSational pun, a small white heart lifted out of the fainted skeletons chest and out of no where a green soul appeared. They... merged? Everyones mouth was wide open, except for sans, as he always smiles.

The most shocked was sans as he knew what they were. "Hey, we should call a doc-" Denki was cut off by Sans. "No... no quirk can heal this, its already been absorbed..." That left everyone in even more confused. Quirks could so anything... right? "Welp I guess I have to explain now. Me and a few other people, including Papyrus have something called a soul. They all have mutant quirks. But only 7 normal humans without mutant quirks have a soul. Our souls are white, while the humans ones are 7 different colours. A monster can absorb a human soul, but a monster can't absorb a monster soul and a human can't absorb a human soul. Think as it of a super rare quirk... though... I don't know how my brother absorbed a human soul in his sleep..." Sans finished.

Everyone looked at him only to find his eyes are gone. It was better than he didn't go into the story of Mount Ebbot or the resets. They would be traumatised.

Well that killed the mood. "So what will happen to Papyrus!" Mina said, trying to keep up her cheery aura.
"Nothing much, his appearance will change making him look more human, he will be even more kind, he can sense when you're sad and he will be more powerful. More powerful then you could ever imagine."

Todoroki look worried, Izuku was muttering like crazy and everyone was just plain scared. More powerful?! He is already one of the most powerful person in the class!!!

The reason Todoroki was worried... well... he could see through expressions and see what someone was feeling... what would be think of him...?

Just after that though he woke up. Their visions seemed to blur a bit untill... he was human? He was taller, had white hair and pale skin. "EH? BROTHER? AND CLASS?! WHY AM I IN A HOSPITAL? AND WHY ARE YOU ALL HERE?!" Papyrus shouted.

Jeez he was loud...

But at least he was the same. "Uh, Paps you might wanna look into a mirror, before the monster in there gets you." Sans said. He chucked a bit, telling others it's a joke, but leaving everyone including Papyrus in the dark. "Wait... someone in here is not right..." Papyrus said pointing at his soul. "OH! My soul hurts whenever someone within a 200 meter radius is hurting, mentally of physically." He said, exploring the room, using his soul as a guide. It hurt the most the closer he is.

Todoroki sweatdropped. Sans wasn't lying about about it. Sans also sweatdropped. He was hoping it was fake but it seemed real.
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"Are... you ok Todoroki...?" Papyrus asked the now quivering boy. "I-I am sorry I-I-Im supposed to be a h- hic- hero." There was no point holding it in anymore. While everyone was still staring in shock, Papyrus went over to console him. Everyone was expecting Midorya or someone, he always smiles, but Todoroki?

Not long after, Recovery Girl walked in, saw Papyrus consoling Todoroki while everyone except Frisk and Undyne was staring in shock. They were looking for towels. Aizawa was called in, disrupting his midday nap.

He knew it was urgent, as he was only disturbed by a teacher if something happened.

He went in the room to see his scene of madness: a human Papyrus was consoling a crying Todoroki and Frisk and Undyne were cleaning up the tears with towels while everyone just stared in shock. He needs a raise.

Everyone just tried to explain what happened but failing miserably. Sans explained everything, including the souls. He seemed more shocked than usual, his eyes 0.01 millimeter wider. That's really rare. Only 1 person have ever seen it.

It... was shocking.
Todoroki was to go to therapy, and Papyrus was to go to recovery Girl to test his new abilities. According to sans, he could be more powerful then All Might himself...