Disclaimer: Undertale belongs is Toby Fox's mind child and all the praise and profit belongs to him. This work of fiction in purely a fan creation.
[[Welcome To The Surface]]
11. Oblivious of the past
After one week from the day they came up to the surface, Toriel had now many unexpected impressions about this new world, about its inhabitants, and about her child. Apparently, about one year ago, Frisk had gone to adventure with Luke and other two children. They stopped at Cebark for some reason, reaching the statue named 'the tragedy of two souls'. Her child stared at the memento for two days before making the definition to head Mt. Ebott. Their teammates did not agree to go with them. Luke was the only one who promised waiting for their return.
A month later Frisk fulfilled the promise, but now they had become ambassador of the underground monsters. Toriel looked back at the silhouette of the brave child sleeping beside her. They shared the sleeping bag with the gorgon child. Their lidless eyes were hazy. It was the sole hint Toriel had for knowing the kid was sleeping. Inside a whirlwind of thoughts invading her mind, anxiety was taking its toll. There was not any hint as for why Frisk had gone down Mt. Ebott in the first place.
"Can't sleep again?" Sans had made Bocco's empty nest his official bed now.
"Oh, I hope I did not wake you up." It was early in the morning and the sun had not arisen yet, it was still too soon to start the day.
"nah. i'm awake." He said, even though he had the eye sockets closed. "do you feel like hanging out?"
"…yes, let's go."
He stood up at such speed that in a blink he was waiting for her by the main entrance, his signature smile bigger than the usual. Toriel unraveled the blankets making less noise as possible and then she walked out with him. She gave him the paw and, by the next second, they were in a place Toriel never expected to see again, Sans had transported them directly on top of a bed of golden flowers in the underground ruins.
The aroma of buttercups mixed with the cold night burned a little her nostrils. A sense of tragedy and nostalgia clenched her heart. She turned at the skeleton with a mixture of wariness and curiosity.
"What are we doing here?"
"i always wanted to see your side of the door." It was so silent, that the clacking of Sans' bones when he shrugged echoed around. She had lived in those ruins for more time than she could count, she knew every corner and every hiding spot, all of them traced a map in her memories. She couldn't get to hate her self-imposed imprisonment. This had been her home for so many years. If it wasn't for Frisk, who knows if she would ever gather the courage to stop Asgore or to meet face to face with Sans. Sharing this place with her skeleton friend was the last thing that passed thought her mind when she used to tell him pranks behind the door.
"Sans, I need you to ask you something about Frisk." In the darkness, only the spots of Sans' eyes were barely visible. He was about to lift the spirits with a pun, but Toriel cut him straight. "You know something about them that no one tells me."
For a couple of minutes, some liquid dripping on the rocky ruins was the only noise filling the air. Her friend's silence was an invitation to the sense of dread from which she was running away. Maybe she had touched a nerve on Sans. She held chuckling from her inside pun. But once he started speaking, there was no longer place for laughter.
"there's an anomaly of the space time continum in the underground."
For whatever Toriel was expecting to hear, this was way on the bottom of the list. He continued with his most serious tone.
"you may think it's the first time we get to the surface but, according to Frisk, this has happened so many times the kiddo has lost count of them." Sans invited Toriel to take a seat on the bed of flowers, because what he was about to explain was a story actually longer of what it lasted in reality.
Sans started referring to the child story as 'the anomaly'. He told her what Frisk had confessed him some days ago. One day, the child woke up where they were standing now, on that very bed of golden flowers. Without a single memory of who they were or what they were doing in that place to begin with, they wandered off until they met Toriel in the ruins. Frisk thought that maybe there was a place they could call home on the surface; it was nothing but a vague idea. They kept going out of sheer determination to figure things out.
They followed the path towards Asgore following their internal voice. At first, they reacted to the dangers in the underground as any person from the surface would do: they fought. Under Frisk's perspective, monster down there were up for murdering them. So Frisk killed froggits, childrakes, and tsunderplanes for protecting themselves. Then they faced Asgore, and then they won.
However, crossing the barrier eventually took them back to the flower's bed at the ruins once again, remembering every action from their previous attempt to escape. Frisk thought that by recreating their journey to the castle, it would give them the same results. However, it was impossible to repeat the same patters. They changed little things here and there, sometimes involuntarily. They took different approaches, said different things, killed or spared different monsters.
Over and over again.
They came back to the bed of flower whenever they crossed the barrier. Frisk no longer was sure in which timeline they had said this or that, at some point this made them hesitate over their actions about if they were heading to the correct path. More than once their hesitation took them back to the bed of flowers even before reaching the barrier or facing Asgore. Frisk matured during this journey, because they lived the same route for such a long period of life.
Eventually, this endless circle made Frisk grow into despair. They knew all the underground monsters at such extent, that they considered them a new family. Nevertheless, not even kindness can overcome repetition. If monsters had a claustrophobic feeling for not being able to see the sun, it was easy to imagine how Frisk felt trapped underground and on top of that in a time loop.
They grew tired.
Then the child took a path that they are not proud of, a genocide path. Toriel couldn't believe her ears about the atrocities her gentle child had committed, from when they felt they were above the consequences. After leaving the underground empty and passing through the barrier, they were back on the same restart over the bed of flowers. She believed in Sans' words blindly, especially since they were a confession of her child. More than ever, she wanted to hug Frisk and tell them that whatever burden they had carried it was not the use. They needed to know she forgave them for killing her in another timeline. Now the tears couldn't stop flowing down her cheeks.
"frisk was so ashamed that they were ready to reenact the nicest person in the world a thousand times for washing up their sins. it wasn't necessary, because when fighting asgore for once SOMETHING had changed…"
Toriel raised her head to look at Sans pausing the story. His smile was authentic and up to his eyes.
"it was you."
"What do you mean?"
"you came to save them from committing the mistake of killing the king one more time."
For Toriel it was very unreasonable to leave a kid wander alone through the underground. She had made that mistake with the other children, six souls that she had let go while she hid in exile as if that was doing any good to anyone. After hugging Frisk at the outskirt of the Ruins, Toriel's guilt pushed aside her fears and made her return to the castle to protect her child. She didn't waste time in Snowdin or Hotland, she head to New Home believing in her pun pal's promise to keep an eye on the child during their journey.
She couldn't have been more thankful when news came to the city about the child who had befriended the robot that appeared on television. Toriel headed then to the castle and arrived to the barrier just in time to save the child. It was something that had to be done, and the idea that in another life… in another timeline she had neglected Frisk as she had done with the other children… it repulsed her.
Author's Note: I've read a lot of fiction where Sans is completely aware of the resets and angst ensues. However, I like to think he's just good to figure things out by people's reactions. Frisk eventually confessed Sans about everything and the skeleton decided it was not worth risking the kid's reputation for something that technically never happened.