Warning: Character death. Like depressing, I am amazed I even wrote that, I am a monster character death. Read at your own risk, cause this is really sad. It will only get fluffy later.
The barrier was broken. The human had finally done it. It took them reset after reset, but they had finally figured out how to break the barrier without dieing.
As Sans watched over the unconscious kid, the others all rushed over the the room that had once held the barrier. They had felt the bars to their prison snap, and they wanted to be sure that it was truly gone.
That was when Sans heard the cries of dismay. His heart sunk. Was it not broken? Were they still cursed to the Underground?
As he waited for the others to return, he watched over the kid, desperately hoping that he was wrong, that it was over and the kid would never feel the need to reset again. He didn't think he could stand the thought of going through it all again, especially after being so close to the end.
He heard the kid groan, and gently patted their shoulder to try to wake them up.
"Hey kid, wake up. The others are worried about you." The kid sat up in response, rubbing their eyes.
"Did it work?" They asked, hopefully.
"Let's go find out, huh? The others are waiting for us there." Sans led the child to the other room, and the two stopped in their tracks when they saw it.
"Do you think we could still go through it?" Undyne asked quietly, referring to the new barrier that stood in front of them. It was clearer than the old one, allowing them to see through it to the surface.
Always the one to lead, Undyne walked straight up to the barrier, and held her hand up to it. When she felt no resistance, she just walked right through it. The moment she was all the way past it, she suddenly started to scream. Magic poured off of her in waves, and she shrunk at the strain on her magic. And it just kept draining. Alphys ran forward, trying to support Undyne, only to suffer the same fate.
When they finally settled, no longer losing magic, they were maybe the height of Sans' finger. The couple tried to re-enter the Underground, only to be stopped by the new barrier.
It was only one way.
They were free, but the cost was too high.
Undyne tried to speak, but all that came out was a garbled noise, as she was unable to muster even the microscopic amount of magic it required to speak.
The next few hours were spent trying to find a way to break the new barrier. They threw attack after attack at it, only for them to be absorbed like it was nothing. Other monsters started to arrive, the news that the barrier had been broken having spread. None were let through the barrier, but they also helped to attack the new barrier, trying to test its limits. Even after the monsters had expended most of their energy, the "Draining Barrier" as they had taken to calling it was still unbroken.
Then the humans arrived on the other side. Where Undyne and Alphys were still recovering from having their magic sapped from them. The humans picked them up effortlessly, holding them up for inspection. They liked what they saw.
Asgore, enraged at the treatment of the two he almost considered his children, barged through the barrier without thinking.
It seemed that even being a boss monster wasn't enough to save him from the draining effects of the barrier, and the humans were only more excited to see the process for themselves. They saw the hordes of monsters on the other side of the Draining Barrier, and their grins grew predatory. They seemed to call for more humans to come, and Sans could just barely hear them through the Draining Barrier.
"Hey Boss, you've got to send some guy over here, to Mt. Ebbot. We've just hit the jackpot! There are these weird monster things behind some sort of barrier, but get this. Every time one of them come through, it's like they shrink. Like they are losing what keeps them together or something. They are so adorable, and seem to be harmless. We could sell them for a huge profit!"
Sans saw red. He summoned as many blasters as he could at once, and sent them all at the men. Not a single one got through. The humans had the nerve to laugh at him.
He started to huff at the excursion, and then realized the odd looks that all of the monsters were giving him.
"What? Can't a guy get angry?" He said, trying to wave it off. The Underground responded by starting to shake.
"Oh come on." He joked, before starting to look uneasy as the ground continued to shake. Parts of the wall started to crumble, and dust was raining down on them.
When the ground finally settled, the monsters were left with an uneasy truth. The Underground wasn't safe anymore. The barrier had held the mountain up, even with the giant caves, and with it gone, the whole Underground was collapsing.
They had to leave. Out of the frying pan and into the fire, it seemed. From one prison to another.
Sans looked down at a tug on his sleeve. He looked down to see Frisk with watery eyes.
Right. The reset. Frisk could just reset, and it would all be fine. They could just never try to get to the surface again, or find a differ-
"I can't reset. It won't work." Oh.
There was a crashing noise behind them, and they heard screams. A boulder had fallen from the roof, right into the middle of the crowd. Monsters were crumbling underneath it, creating a panic. They rushed for the exit, choosing an uncertain future over a certain death.
They only had to travel out of the initial clearing, humans waiting just out of sight of the barrier, and of the full sized monsters.
As they ran out, the humans were waiting, capturing them with ease. It was only when Frisk was revealed from behind a shrinking Toriel they paused.
"Stop!" The child shouted, gaining a pause from many of the other humans. "You don-"
Frisk was cut off when one of the humans grabbed them and started to walk off. Sans acted quickly, fighting through the pain of his transformation to cling to the child's boots, effectively hiding.
The other human moved on quickly from the encounter, and in the rush to capture the inflow of monsters, some even forgot about the child completely.
Frisk was dragged to an area that held only a few humans, all dressed up in nice suits.
"Found a little rat in with the mice, sirs" The man said, his voice only serving to make Sans angry. He was too weak to do anything about it, though.
"That's the kid that went missing a while back! They are already considered dead by the police, and the search for the body was put off ages ago." Sans did not like what the man was insinuating.
"Kill it. I'd cause too many questions, and we can't afford that if we are to make any profit off of this." Sans definitely did not like where this was going. As he tried to muster up his magic, to do something, anything, to save Frisk, one of the men dragged them off into an isolated clearing, before taking out a handgun. The child struggled as hard as they could, but were unable to break free.
Sans couldn't stand to watch, closing his eyes, feeling helpless. He couldn't even save the kid he almost considered his own child. He hugged the kids leg, his sobs masked by their muffled screaming.
*BANG*
Frisk fell, the angle nearly squashing Sans. He tumbled out of the way, looking up to see the human walking away. The coward couldn't even stick around to observe the consequences of his actions.
Sans ran over to their head. The kid met his eyes, tears streaming down both faces.
"I'm so sorry kid. I let you down, I couldn't save you, even when I was right here. I couldn't save you." He sobbed clinging to their cheeks. A hand wrapped around him in what he assumed to be a hug.
"I love you Daddy. I'll miss you." The hand fell lax. Moments later, a soul drifted out of their chest. They were gone. They had finally called him daddy, and now his wonderful little adopted child was dead. There would be no resets, he would never see them again.
Suddenly, Sans fully understood Asgore's oppresing hate of humans. But Sans refused to hate all of them. Even Asgore's adopted child had been evil, but Frisk was the shining beacon that told Sans that not all human were evil. So he wouldn't destroy all humans. No, he was going to kill every last one of the humans on the hill, he was going to get revenge for his sweet little Frisk.
Plan in mind, he reached for the small red soul that hovered above the child's chest. As he absorbed it, he felt a rush of power. He convulsed under the power of the soul, but even as he felt himself growing stronger, he knew it wasn't enough. He wouldn't have even be able to hold a candle to the him from a day ago, much less against countless humans.
He collapsed against the chest of the cooling corpse. He felt like an utter failure. He couldn't even save Frisk, nor could he avenge them. It was hopeless. He was only able to watch as his world crumble around him, even when it was supposed to be the best time of his life. They had finally broken the barrier after 10 separate resets. But it wasn't enough. Now Frisk lay dead at his side, and he was too weak to do anything about it. No reset would come.
When the humans came back, they picked him up, moving him away and again all he was able to do was watch as they took the body, burying it at the base of a cliffside.
He was shoved in a cage with monsters he didn't know. He was shipped to places he didn't know. Eventually, he was dumped into a pet shop, to be adopted like some casual pet. He didn't care. He just didn't care anymore.
AN: Wow. That got dark fast. Poor Frisk. Poor Sans.