Despite the dire circumstances, despite the danger to his brother, and despite their massive plot that was highly unlikely to succeed, Sans would be hard pressed to say he didn't have any fun at all when he destroyed the Pure base.

The second that Gerson and Undyne stepped far enough back to not be considered in the base, he opened his right eye and let loose the Magic that had been fighting to take him over.

He tore into the buildings with wild abandon, destroying everything in his path, then turning around to destroy it again. He ripped apart walls with his bare hands. He sent attacks shattering through the ceilings. A building or two may have collapsed on top of him, but he was too far lost in his wild frenzy to notice.

Eventually, he calmed down, and quickly slapped his hands over his right eye, trying to stifle the power surging through it. After a moment, he lowered his hands, eye closed.

Then, with his left eye, he surveyed his work.

There was nothing left. It was all just rubble, shattered wreckage spread across the entire cavern.

Gaster had explained once to Sans about hurricanes and tornadoes. He had said that the atmospheric region in the top of the Underground that created snow in Snowdin and rain in Waterfall wasn't quite strong enough to create gale-force winds, but he had made it quite clear to Sans that this was a good thing.

Looking at the wreckage, Sans thought it must have looked like what would happen if two or three tornadoes had gone through there.

He turned around. Undyne and Gerson were still standing in the same spot. Even from this distance, Sans could see their mouths were open.

He gestured for them to come on.

A bit hesitantly, they followed after him as he started walking towards Snowdin.

~o0o~

Gaster felt so helpless.

There was nothing he could do.

And now Papyrus was being Corrupted, and he was stuck in this cell.

Almost immediately after Sans had left, Chara had come into the cell, wrenched Papyrus out of Gaster's grip, and dragged the small skeleton over to the operating table.

When they had filled a syringe with Corruption, Gaster had shouted that they had promised not to hurt anyone.

Their response had been that it was all a matter of opinion, that they considered being Corrupt helpful, not harmful. Then they had plunged the syringe into Papyrus's Soul.

And then they turned to look at Gaster and laughed. "In any case, haven't you ever heard of lying? It's quite useful. You should try it sometime; there are so many things you can do with it."

Now Gaster was stuck, sitting in the cell, as Papyrus moaned and whimpered and struggled weakly against the restraints on the table.

To make matters worse, Gaster was also in pain; his ribs were cracked from Chara's blow, and he had received more wounds than he originally thought when initially rescuing Papyrus. Not that that mattered, he could put up with a million more times this if it meant relieving Papyrus of his pain.

Gaster looked at Chara, who was standing nearby. "Why are you doing this?" He made no attempt to hide the pain and desperation in his voice.

They looked curiously at him. "Because I'm the evil overlord."

Gaster blinked. "But... why? When I knew you, you were... well. I won't say you were nice, because you were a very rough child. But you were by no means evil. What-... what happened?"

For a moment, Chara seemed very absorbed in looking at their fingernails. Then they looked at Gaster, a fire burning in their reddish brown eyes. "They say it's a bad idea for the villain to start monologuing, and in every movie I've seen and book I've read, I scream at the villain when they reveal their plan because it's always their downfall. But I'm so beyond caring now. It doesn't matter, not anymore. So I'll tell you. I'll tell you. I died. Killed by Corrupt monsters. And Asriel absorbed my Soul, and I led him to go take my revenge. But even with the power of a human and a monster Soul, we weren't strong enough to take on the Corrupt army. Even as we ran, we died.

"But even as the breath slipped from our lungs, as we crumbled to dust, there was something else in our Soul. In my Soul.

"Do you want to know what it was? It was hate. Hate for this world, this world that has to extinguish every light, that can't let such a small good thing as Asriel live. I hated this world for killing my brother. I wanted to see it burn. And holding onto that hate, I called out to the Corruption.

"For a little while, I let the Corruption hold me. Then, I fought it, I won, and I took control of it. Because, see, the Corruption is hate. I am made from hate. That, combined with my Determination allows me to live again, to rule this Corruption, this instrument of the world's destruction."

Chara paused a moment in their monologue. "You see?" They asked Gaster, smiling. "You can't kill me. I'm not alive, not really. Just hate and Determination. I am ruler of the Corruption, it obeys me."

"... So this entire thing is a revenge plot?"

Chara laughed. "Ha! No. I mean, that's a big motivation, but the Corruption was around for a long time before I was even born. It's been hating for a long time, it just accepted me as its complete monarch when I proved to be stronger than it."

Gaster blew out a slow breath. Honestly, he had no pity for Chara. They had hurt his sons, and he couldn't forgive that.

Heh. The irony of it. He supposed he was the "good guy" here? But Chara hated because their brother had been killed. And now, here Gaster was, hating Chara for hating.

But. His sons were still alive. He wasn't going to let them die, regardless of how hypocritical he was.

"So. What exactly, then, did you do to make Sans go into a Soul-hungry frenzy?"

Chara laughed again. "Sorry, doc. I'll have to draw the line at the backstory. If I start describing how my plan works, it really will be my downfall. That's just how these things work."

Before Gaster could say anything, the door was kicked in. "But, see, it's already too late!" A loud, familiar voice screamed. "Because we're gonna kick your butt anyway!"

"WHAT THE HECK-- WHERE DID YOU COME FROM?!" Chara screamed at the fish monster and tortoise who stormed into the room, weapons drawn.

"eh. y'know, i brought 'em." Sans sauntered into the room. "couldn't let you go hurtin'..."

Despite Sans' confident entry, Gaster could see he was struggling. He had his right eye closed, and was sweating. This was only magnified when he saw Papyrus, still fighting the Corruption in his Soul, prone on the table.

His expression turned murderous. "undyne. gerson." He growled. "change of plans. you get my family outta here. i'm takin' on this brat myself."

Before anyone could argue, Sans and Chara were locked in combat, Sans' broken left eye blazing with Magic, the Corrupt Magic already running down his face as he refused to let his right eye light.

But Gaster didn't have time to watch as Gerson forwent the electronic door lock and just smashed in the cell wall with his massive hammer. Then he was grabbing Gaster, hoisting the Royal Scientist over his shoulder, and running out of the room, Undyne carrying Papyrus right behind him.

~o0o~

As soon as he was sure that Undyne and Gerson had had enough time to get down the hallway, Sans took a shortcut to the doorway, struggling to simultaneously block out the pain of using his Pure Magic and stop his Corrupt Magic from overtaking him.

Chara raced after him as he slipped out the door and started running in the opposite direction he knew Undyne and Gerson would have taken.

Chara ran after him, roaring in fury, intent on destroying him.

Good.

He led them on a wild chase, letting them think he was going to stop and fight them, occasionally firing an attack off behind him. They followed, blinded by their anger.

Eventually, he found what he was looking for: a large, empty hallway.

He took a shortcut into the middle of the hall.

Chara entered cautiously, waiting for his attack. He didn't attack, not yet.

They walked up to him.

He chuckled. "well, kiddo. this is it. your final chance, then. drop the knife, walk away. leave my family alone."

"Or what?" They snarled.

"or you're really not gonna like what happens next." Sans got ready to feed more Magic into his broken left eye. He knew he was going to need it.

Chara grinned darkly. "Actually, I think I'll enjoy killing you."

Sans shrugged. "fair enough. y'know, kid, it's a beautiful day outside. the birds are singing. the flowers are blooming. on days like these, kids like you, S H O U L D B E B U R N I N G I N H E L L ."

Even as Sans' one-eyed vision lit with a blue and yellow glow, Chara was grinning. Their eyes turned pitch black, sticky black tears dripping from their eyes, black drool running from their mouth.

"I͚͈͕͉̰̰̿͂ͧͪ̿ͪ ̵̵̳͎̭̭̐̾ͬ̈̏͌̒ ͕̪̦̬̳̳͙͌͂ͬ͛̀͜ ̨̩̖̜̘͖̭̺ͤ́͋̽̀͐A͚̗̹̫̲̾̃͗ͫ͐͛͒ͨͅ ̷̸̮͖̣̳͓̱̣̪̱̔̈́͢L̫̤͇̤͖̱̔̇̽͋͂̄͟ ͉̭̔ͦͨ͒ͤͥ̚͘͢͝R͊ͪ͆̈͟͏̧̪ͅ ̘͙̺ͣͨͦ̎É̵̤̹̜̝̣͕͙͛̀ͅ ̛͍̘̝̤̜̙̬̀̋ͯͦͤ̊͐͒Ą͕̤̯̼̺͌̕ ̦̲̱̰̺̓̊͐ͦ̆ͥD̝̜̮̘̘͕̹̏̓ͪ̌ͮ̂̐̈́͊ͅ ̸̝̦̐ͦͪ̒Ỵ̢̞͖̒͛́ ͓̥̰̹͔͍̊͐̐͒ ̘̱̅͌̉̓́̂̓͠͡ ̢̝̮͓̼͕̲͍ͨ̑͋͌̈̉̚͡H͎̘͖̝̦͂̔͊̌͋̾̐́͘ ̶̣̬͓͂̋̇̑͋͒̿̽Ă̵̊̄̔ͪ͏̘̠͓̲̲̝̹ ͙̍͒ͤ͘̕V̵̪̳͕̠̰̅͐ͫ͋ͭ ̶͙̳̥̞̽͌̒̉ͯ̑͋̐Ȩ͆̏͂́͏̺̯̲͚̫ ͇͚͎͎̻ͣ͐̾ͮ͆ͪ͝.̿ͮͥ͏̜̫͢ ̢̺̭̳̟̝̜̂̈͢"

~o0o~

Gaster was almost ready to throw a tantrum.

Because here he was, being carried to safety, while his son fought an unkillable beast with less than half of his arsenal.

But he had to trust that Sans knew what he was doing. After all, he had gotten Gaster and Papyrus out of there. Maybe even that "change of plans" was actually all part of his plan.

Gaster had to believe.

Suddenly, they slid to a halt. Gaster was dumped off Gerson, and Undyne handed the still-unconscious Papyrus to him. Tearing his gaze away from his son, Gaster looked at why they had stopped.

He whistled. "That is a lot of Corrupters."

Undyne gave him a scathing look. "No duh."

And then they started fighting.

~o0o~

Sans fought with everything he had.

Which, unfortunately, didn't mean his Corrupt Magic. Because, the second he started using that, he knew, he would stop fighting Chara and let his Corrupt lord kill him.

So that meant keeping his right eye closed. Using broken Blasters and splintered bones. Pushing and shoving with Blue Magic.

Dodging and taking shortcuts out of Chara's attacks, because he knew he would go down with just one hit. If they touched him, it was over. He was done, dead, and not even his strange mixed Magic would be able to save him.

So he dodged and attacked.

Chara just laughed, a howling, shrieking, grating sound that hurt Sans, every time they got hit. They got hit a lot, the same sticky, black liquid dripping from their wounds as their mouth and eyes.

And the battle went on.

Chara sliced at Sans with their black knife. He dodged back, simultaneously lifting his hand and firing off a pair of Blasters.

Chara dodged one, only to jump straight into the other. Their screaming laughter sent a chill down Sans' spine.

He couldn't keep this up much longer, he knew.

They lashed out again, and he took a shortcut behind them, then sent a multitude of broken bones to run them through. All were dodged or blocked.

He would be hit, and he would fall and die, and then Papyrus and Gaster would die, too.

They would all die.

Sans slipped under Chara's next attack, then used Blue Magic and a shortcut to move them a ways away.

Breathing hard, he watched them advance. As soon as they got within reach, he shoved them back again.

"... What is this, Sans? Done fighting?"

Sans panted. "heh. yeah, pretty much. i- i know I can't beat you. you'll hit me sooner or later. so, uh- ... i'm jus' not gonna let ya get close enough to hit me. or anyone else. ever. even if it means we're standing here 'til the end of time."

Chara just smiled. "Okay, then." And they sat down on the ground.

Sans waited. And watched.

Annoying Dog, he was tired.

Chara didn't move. Neither did he.

He had used so much Magic, and more of it had leaked out his eye. He was quite practically running on fumes.

He felt his left eye begin to close. Chara tensed, but didn't move.

He had come into this knowing he wasn't going to make it or alive...

N- ... No. gotta... protect Pap...

Chara lunged. Sans twisted his Magic as he dodged. A wink at Chara, and then he was gone, taking a shortcut away.

~o0o~

They had just finished off the rest of the small mob of Corrupters. Gaster had taken quite a few hits, but he was still standing, and Papyrus was unharmed.

Suddenly, Sans collapsed in front of them.

Still clutching Papyrus to his chest, Gaster ran over to Sans as he climbed shakily to his feet.

There was a literal stream of Corrupt Magic flowing from his eye.

"Sans," Gaster began, "what-"

Sans waved him off. "no time for that. two hallways down, left turn then straight. sixth door. gotta get there."

"What's there?" Gerson asked.

Sans gestured vaguely to his right eye.

"Alright, let's go."

They started forward, but as soon as Sans tried to move, his legs collapsed beneath him. Luckily, Undyne was there. She caught him, and slung him over her shoulder. Then they were running.

~o0o~

Sans fell into an exhausted daze as Undyne ran. He had directed them to the... thing that was amplifying the Corrupt strength. All they had to do was destroy it, and things would get a lot easier.

Gerson was running in front, then Undyne with Sans, then Gaster with Papyrus. Sans was happy to see Gaster was mostly okay enough to be running. Papyrus was unconscious, and probably in a lot of pain, but he was alive, so that was something.

Undyne turned left, then went straight. Sixth door.

She twisted Sans in her grip. "This it?"

Sans looked at the thing. "that's it."

Undyne settled him back on her shoulder, then started flinging attacks into the Corrupt thing, alongside Gerson. Eventually, once they were sure it was broken beyond repair, they stopped. Sans could feel the Corrupt power slipping from him. He opened his right eye. It was okay.

"What now?" Someone asked. Sans wasn't quite sure who was who anymore. He was just so tired.

"now," he murmured, "...now i do this."

He poured Magic into his left eye, grabbing all their Souls with Blue Magic, and pulling them through a shortcut.

~o0o~

As soon as the darkness faded, the crushing pressure in his chest had released, and he heard Sans coughing and gagging and choking, Gaster understood what had happened. Sans had shortcut-ed them back to the lab.

He pulled himself up and moved over to where Sans was lying on his back, choking on his own mixed Magic vomit. Gaster sat Sans upright and lightly pounded on his back, until he was finished.

From there, ignoring the pain wracking his body, he lifted Sans onto the table, and located Papyrus as being curled up on his side on the floor.

He swooped down and grabbed up Papyrus, then settled him next to Sans' side. Sans smiled at Gaster and held Papyrus close.

Undyne and Gerson were regaining their feet.

Sans had been using his Pure Magic again, so that meant Gaster would need to clean out his eyesocket again. He gathered up what he would need, and returned to Sans, noticing with some relief that Sans seemed exhausted, but still more or less fully conscious.

"Are you alright?"

"... yeah... didn't get hit once... just used... lot'a magic... pretty nauseous."

Gaster nodded. "That's good you didn't get hit, I suppose. Need to get you cleaned up, though. Can you hold still?"

"mm'kay."

"Doctor-" Undyne began, but Gaster waved her off. Sans was priority, at the moment, then Papyrus.

Gaster started to clean Sans up.

As Sans was awake this time, he was able to hold still throughout the whole of it, and didn't take as long. As soon as Gaster finished, though, Sans promptly closed his eyes and went to sleep.

Before Gaster could do anything else, though, Undyne grabbed his shoulders and forcibly turned him around.

"Doctor. Stop. Sit down."

"What? Why?"

"Just do it."

Gaster couldn't sit down; he still needed to check on Papyrus-

Then he happened to glance down.

He remembered taking hits when he fought to save Papyrus. The blow from Chara that had knocked him out. Getting hit more when fighting alongside Gerson and Undyne.

He was a scientist. Not a soldier.

The damage just added up.

Finally, Gaster was forced into acknowledging the pain that besieged him. His vision blurred and his knees felt weak.

Did he even have ribs anymore?

Or had they all already turned to dust?

His legs gave out, and he plummeted.

Undyne in font of him. Holding him up. The Gerson.

Shouting.

Go get help!

Yes. He wanted to go get help. Someone needed help. Papyrus. Sans. Himself.

Help.

Hurts so much.

His vision started to get black.

Hasn't hurt like this in a long time.

Just stay still, Doctor. Undyne's gone ta get help. Stay still.

Still?

He could do still.

He could stay still...

...So still...

§

A/N

Geez. Poor Papyrus always gets the short end of the stick when it comes to the Corrupt base. He always ends up unconscious. But, then, everyone's pretty much passed out now.

Thank you so much for reading, and I sincerely hope you enjoyed it! Remember, comments and votes are not only always welcome, but always appreciated, too!