Corrupted Timeline: UF!Sans X Reader

Strange cave in Mt. Ebott

"Alright", you say to yourself. You hear your mother calling from downstairs. "Are you ready to go?"
"Yeah!" You pack the last of your things in your backpack and head downstairs. Your parents are done with their packing and see you coming down from the stairs. Your dad was the first to speak. "Are you ready to hike up Mt. Ebott?" You nod your head. "Mhmm!"

Your mother gives you a plate of toast for you to eat. Your father packs your things into the car.
*Time skip*
You and your parents make it to Mt. Ebott and found a place to park. "Alright, we're here!" Everyone grabs their backpacks and then you all start hiking up the mountain. When you reached the top, you see a breath-taking view. It was such a beautiful scenery. Your family takes a photo together at the top of the mountain. After spending a few hours hiking, your family decided that it was time to go home. Your father calls to you.

"Watch your step Y/N. You could slip and whatever you do, try not to get lost ok?"

"Ok" was all you said before making your way down.

It was getting dark and it was kinda hard to see. At the corner of your eyes something caught your curiosity. You know your parents wouldn't want you to explore alone, but curiosity got the best of you.

You decided to separate from your family. I mean, a little exploring wouldn't hurt right? You see a cave in a distance and walked towards it. Inside the cave, were small carvings of pictures you didn't understand. It was like a story or some kind of history. You remember that on Mt. Ebott they had a history of humans trapping monsters underground, but you didn't think it would be real. As you were thinking this, you felt as if you were being pushed and your foot slipped. "Shit!" You fell down the hole, and met the ground with a loud *thud* before you lose consciousness.