This chapter was SO MUCH FUN to write, I hope you guys have as much fun reading it as much as I did while writing ^^

We then go to a flashback, where Toriel and Asriel are unable to stop Bill from taking the souls and gaining full power. Sans tells them to run, and then challenges Bill. But the fight doesn't start until after Bill gives Papyrus a trip down memory lane.

Papyrus and Undyne bravely throw themselves against Bill's monsters, but soon realize that Sans is in trouble.

Chapter Text

Some of Bill's monsters could be killed, some couldn't. At the very least, Papyrus and Undyne could cut off a limb or two, enough to slow down the opponent. They were trying to get to the source of all this destruction, and whomever-or whatever-it was very quick to send out a wall of monsters.

As much as Undyne would've loved to drop her spear and wrestle the biggest monsters to the ground, she left those ones to Papyrus, while she handled the smaller creatures. The less threatening an enemy looked, the more likely it was that Papyrus would spare it. And this was a situation where mercy was NOT an option.

But even so, it was almost energizing, racing through the rushing wind, jumping and flipping through the air, landing hits on powerful foes. Undyne easily cut through the enemies with her spear, and Papyrus sent out bone attacks, he could even use his signature "blue attack" on some of the creatures.

Weirdly enough, these monsters didn't have souls; they didn't turn to dust either. All you could hear when one died was a thud, and that was it. These creatures were definitely NOT Underground monsters.

Undyne realized she still had much to learn herself, she was so used to one-on-one fights that she didn't notice when she was being surrounded. Papyrus ended up saving her as much as she saved him.

As the two of them finished off the third wave of monsters, the wind started to die down, just enough for Undyne to see a familiar figure in the distance.

Undyne jumped on top of the last monster she defeated, and looked in the direction of the figure. "Is that Sans? He doesn't look...safe."

Papyrus jumped up next to Undyne and looked in the same direction. That really was Sans, and hovering above him was an ominous triangle shadow, that was slowly growing larger.

Undyne had to hold Papyrus back from running of to save his brother on his own. Little did she know, Sans had watched Papyrus die before, and after discovering this, there was no way Papyrus was letting the roles be switched, especially when he could do something about it.

But it only took Undyne a second to say her piece: "No way, I'm coming with you." She flashed another grin, and with that, they dashed towards the shadow.

A few moments earlier...

Toriel and her son ran towards the location of the souls as fast as they could, following trails of blue magic left behind by rapid teleportation. But at this point, all the speed in the world couldn't stop Bill from getting to his desired "power source."

"WELL, WOULD YOU LOOK AT THAT?" Bill called as Toriel and Asriel appeared from around the corner, "LOOKS LIKE I DIDN'T EVEN HAVE TO GET PAST THE KING, HE ISN'T HERE! DON'T MIND IF I DO, THEN!"

Bill, still in Sans's body, approached the souls. Free from their containers, the souls circled around, drawing themselves towards the nearest creature, which happened to be the triangle possessing the skeleton.

Asriel almost jumped out, attempting to push 'Sans' away from the souls, but Toriel quickly sensed the incoming danger and held her son back from harm's way.

It was like Bill already had the power he wanted before even absorbing the souls, the walls of Asgore's home instantly fell to the ground, another void opened up, and the whole Underground was soon swallowed in a reality-warping version of hell.

Bill didn't change form, or become the ungodly creature Sans was afraid he'd face. Instead, 'Sans' floated upwards for a bit one eye glowing a bright blue, until Bill finally left this body, and soon started growing in size, blocking the entire view of the sky out.

Sans fell to the ground, consumed by pain coming from all the magical energy Bill made him use. The phrases he had heard in his dream were now being played out in front of him.

"You should've stopped me when you had the chance…" "We won't let you get away with this…!" Sans now knew the owner of the unrecognizable voice. Asriel.

Sans struggled to get up, every bone aching, but he wouldn't let things turn out like they did in his dream.

Breathing heavily, Sans barely managed to cut off Bill's last sentence, he turned to Toriel and Asriel. "Run." He pointed a shaky hand in the opposite direction, "run, and go find Asgore. Look for shelter, hide anyone and anything you can."

"But what about you…?" The mother and son said at the same time, although they were slowly backing away in fear.

Sans shook his head. "Don't worry about me; I'll take care of this guy." The pair still looked concerned, but nodded obediently and took off.

"OOH, IS THIS A CHALLENGE? HOW FUN! BUT FIRST, THERE'S A FEW TIIIIINY LITTLE CHANGES I NEED TO MAKE." From the void that was still opened, bizarre creatures of all shapes and sizes poured out. "HAVE FUN, YOU GUYS! THIS IS MY WORLD NOW; FEEL FREE TO SPREAD ALL THE CHAOS YOU WANT!" Bill's monster friends let out an ungodly cheer in response, and they ran away in all directions.

"O…kay…" Sans muttered, trying to hide his panic.

"OH, THAT'S NOT IT, JUST WAIT UNTIL YOU GET A LOAD OF THIS ONE!" Bill raised his hand, and above his palm was the human. Frisk—Chara—whoever they really were, floating motionless and limp. "DID YOU REALLY THINK I'D PASS UP THE OPPOURTUNITY TO HAVE A SOULLESS EVIL SPIRIT ON MY SIDE?" He then separated Chara from Frisk, dropping their body to the ground, while still holding what Chara truly was.

For the first time, Sans saw Chara for what they really were: a dark, wispy evil spirit, with the face of a gleeful and demented child. Giggles erupted from Chara, growing more shrill and persistent by the second. No soul, no desire for emotions, no desire for anything except the destruction of all humans and monsters alike.

But Sans had technically fought Chara before, he could do it again, couldn't he?

"BEFORE YOU GET TOO EXCITED—NO, YOU WON'T BE FIGHTING THIS ONE. YOU'VE HAD ENOUGH OF THIS DEMON ALREADY, HUH? I'M GOING TO HAVE THIS LITTLE GUY RIGHT HERE—"He lowered Chara to the ground—"TAKE CARE OF ANYONE WHO WON'T SUBMIT TO MY TYRANNICAL RULE!"

As horrified as he was, Sans couldn't take his eyes off of Chara, the one who had taken all his friends and family away from him so many times, the one that possessed Frisk and forced them to do horrible things time and time again.

"LET'S GET THIS BATTLE STARTED, SHALL WE?" Bill rubbed his hands together, engulfing them both in blue flame. Sans's eye began to glow brightly, fully prepared to make the first attack…until he heard a familiar voice.

Papyrus and Undyne were dashing forward, attacks ready. "DON'T WORRY BROTHER! WE'RE GOING TO SAVE YOU!"

"Papyrus!?" Sans turned around to see his brother, along with Undyne, trying to save him. "No! Don't-"

Bill saw them almost immediately, "OH, THAT'S GOING TO BE A BIT OF A PROBLEM, ISN'T IT?" He quickly shot some blue fire towards the running figures, intending to trap them in a wide circle, but only Papyrus got surrounded by this magic wall. With a few more snaps of Bill's magic, false images of a certain location and particular people appeared within the circle.

Papyrus now faced a hallucination-image of the bridge just outside of Snowdin—the one where he faced the human—and saw himself along with said human. The child was slowly approaching, while Papyrus had his arms wide open, waiting for a hug, saying that anyone could be a good person if they just tried, that he would help this strange human get their life back on track. And then one swish of the knife is all it took for Papyrus to turn to dust…Bill's hallucination was forcing Papyrus to watch his own death.

But that wasn't the end of it, as the howling wind died down and the human passed through the bridge, sobs could be heard. The scene panned over to the opposite side of the bridge, where Sans had just witnessed all this take place.

"T-that. Little. B-bastard…" Sans muttered to himself between sobs, "This…this is why I don't make promises…! Taking my only family…I can't-I can't…I can't just stand around anymore." He walked over to where Papyrus was standing not too long ago, picked up his red scarf, and buried his face into it, sobbing all over again. Soon, angry wisps of magic could be seen coming from Sans's eye, "I-I'll stop that little demon…if it's the last thing I do…! I can't—I won't—let them get away with this. " He fell into the snow for just a moment, before teleporting away.

The vision was now gone, but the memories were imprinted in Papyrus's mind. He shook, speechless, and backed up, almost hitting the blue wall. "No…No…That couldn't be…that's not what…happened, is it…? Is it!?"

It was, as much as Sans wanted to protect his brother, the truth would've been revealed eventually, maybe not about the timelines, but the events that took place. Papyrus's death, Sans's reaction, and what followed after that.

The hallucination then continued, beginning to show the battle between Sans and the human.

"Nonono…please…no…" Papyrus covered his head, trying to block out the image. "I'm sorry, I'm sorry…I'm so, so sorry…"

And then a spear suddenly cut through the hallucination, Undyne had flipped over the wall, and was now banishing the flashbacks.

"Papyrus, Papyrus, are you okay!?" Undyne rushed over as soon as the job was done, dropping her spear and shaking his shoulders, but Papyrus was trapped in a state of shock, whispering "I'm sorry" over and over again.

Meanwhile…

"Papyrus! Undyne! What did you do?!" Sans screamed at Bill as the circle of fire was formed.

"DON'T WORRY ABOUT THAT RIGHT NOW, WHAT YOU SHOULD BE WORRYING ABOUT RIGHT NOW IS YOURSELF." Suddenly, the land they were covering broke off into a separate circle, and Bill flew them far up off the ground, he clapped, and then the surrounding world turned into nothing but a dark void.

Sans's magic was now going crazy, nearly spiraling out of control. Both creatures in this battle had blue-colored magic, and both were practically wrapped up in it now. The difference was that, with the souls, Bill didn't have to try as hard.

"Let's go." Sans whispered, shooting a gaster blaster straight at Bill, but he simply created a hole in himself and let it pass through. The void surrounding them now turned into flashes of moments from Sans's fight with the human, whirling around and creating an insane amount of noise.

"I CAN TELL YOU'RE AWFULLY DETERMINED, I DON'T BLAME YOU. DETERMINATION IS WHAT GIVES ONE POWER IN THIS UNIVERSE, AND BELIEVE ME, I HAVE ALL THE DETERMINATION I NEED TO GET WHAT I WANT." Bill sent forth a few small monsters, ones that moved rapidly towards Sans, in return, he shot a few bone attacks through the creatures, killing them instantly.

"YA SEE, WE'RE NOT THAT DIFFERENT, YOU AND ME. CRAZY POWERFUL, DETERMINED TO FIGHT FOR ONE PURPOSE…OKAY, WELL, MAYBE THAT'S IT." Sans growled, he knew he was nothing like this twisted creature. What Bill was doing is no better then what Chara had been attempting, and Sans wasn't going to be fooled into thinking otherwise.

In his fury, Sans had summoned up a whirl of magic around himself, and ended up creating several beams rapidly approaching the yellow triangle. Behind Bill, Sans could see the image of himself finally being killed by Chara, on repeat, again and again, never stopping.

But all Bill had to do was temporarily shrink his size in order to avoid them.

"YOU AND EVERYBODY ELSE HERE WOULD ACTUALLY FIT IN PERFECTLY WITH MY FRIENDS; WE'RE ALL FREAKS, IN ONE WAY OR ANOTHER, THOUGH I STILL DON'T UNDERSTAND WHY SOMEONE WOULD RISK THEIR LIFE JUST FOR A SIBLING. MAYBE YOU CAN EXPLAIN THAT TO ME LATER!" Bill shot a beam straight from his eye, one that Sans just barely dodged.

He didn't know why he hadn't figured it out sooner: soulless. Bill was soulless. Just like Flowey was…no chance of gaining any pity or begging for mercy here. It wouldn't matter to Bill who he killed, because in the end, he had no soul to feel remorse.

But the words "just for a sibling" angered Sans even more, to the point where he didn't even notice how much energy he was using up. Gaster blasters and bone attacks came raining in from all sides, but through a series of changing size, shape, dodging, or just pure being unaffected, not any of this attacks landed a single hit on Bill.

Sans fell to his knees, panting. "GETTING TIRED? I TOLD YOU, THE ONE WITH THE MOST DETERMINATION ALWAYS WINS. AND YOU—YOU DIDN'T EVEN HAVE ENOUGH TO STOP YOUR BROTHER FROM BEING KILLED IN THE FIRST PLACE! OR WAS DOOR LADY'S PROMISE REALLY THAT IMPORTANT TO YOU?"

"Urrrgh…!" Sans wanted to scream, but he no longer had the power to do even that. In just a few, futile attacks, Sans had been defeated.

"NOT GOING TO DODGE THIS TURN? THAT'S ALRIGHT; LET'S END THIS HERE AND NOW."

One magic blast from the side, and that's all it took to drain the 1HP Sans ever had.

"Ugh…Ugh!" Sans fell to his side, wrapping an arm around where he had been hit. "Urrghh…! No…! I…I. Can't. Lose. Now…!"

As Bill went on about how he and Sans could've been friends, the skeleton put a hand right over where his soul was, and felt it slowly breaking, soon it would shatter…and then he would turn to dust and die.

He felt lightweight; he felt his body fading away, his spirit draining, his soul cracking.

But it refused.