Disclaimer: I don't own Undertale, it belongs to Toby Fox.

Warning for abuse and suicide implications. I don't think it's not that bad, but just in case.

A mother-and-child pair walked along the road. The younger of the two was wearing a blue sweater with bright purple stripes, while the adult greatly resembled her child in skin color and hair. Frisk was playing with their fingers, occasionally looking up at their mother uncertainly. They weren't sure if it was a good idea to speak up, but curiosity won out.

"Mom, where are we going?"

"To that forest you like so much."

They responded with a broad smile, now they were excited. Their mother was referring to a rather infamous forest many people stayed away from because it was near Mt. Ebott. Unlike them, Frisk knew that it wasn't a dangerous place. It wasn't hard to avoid the path to the mountain.

They came across a familiar dirt path, and a clump of trees weren't far off. Frisk's mother took a water bottle from her purse and handed it to her child.

"I have to go to work early today, so I can't watch you. Make sure to behave."

Frisk wasn't sure how one should properly behave in a forest, but they nodded anyway. They were more concerned about mom leaving them alone for the day. She never done that before, and Frisk felt a prickle of anxiety creep up in the back of their mind. Suddenly, they came up with a alarming scenario.

"Mom… you're going to come back for me, right?"

Their mother nodded. "Right."

Frisk grabbed a hold of her shirt with one hand, staring with a pleading look. "Promise?" They didn't want to be left alone, no matter how uneasy mom could make them.

She sighed, took the child's wrist and yanked it away, but smiled gently down at them. "I promise."

Feeling reassured despite the growing pain in their wrist, Frisk turned away from their mother and ran off as quickly as they could while shouting a goodbye, excitement building up again. They didn't stop running until they knew that their mom wouldn't be able to see them anymore. Actually, they didn't stop running until they tripped.

Holding back a hiss, Frisk sat up and rolled their sock down on the leg with a sting. Blood was welling up, but not quickly enough to worry them. They reached into their pocket, took out a bandage with dried blood already on it, and stuck it over the wound. Thankfully, the old bandage was sticky enough to stay on, and their sock didn't get ripped either. Frisk stood up, and took a few careful steps forward. They saw that their water bottle was only a foot away from them. They picked it up and brushed off any dirt that was on it. They sipped from the bottle as they walked through the leafy expanse. The covering from the trees provided plenty of shade, which Frisk was grateful for. The sun made their sensitive eyes hurt.

Frisk swung their legs back and forth while sitting on a thick branch. It was hard for them to stop grinning. They finally reached the top of a particularly tall tree. For the first time in a while, they felt proud. They had never done it with this specific tree before. As they climbed down, they had a idea. After coming to the bottom, they wrapped their fingers around a branch, and pulled hard, causing it to break off. They wanted to keep a part of the tree with them always.

They kept their drink very close to the tree, and made sure grab it. While carrying two items didn't require a lot of work, it did keep their hands full. They sort of wished they had somewhere to put all their stuff in. Maybe something like a box.

Finding a comfortable patch of grass, they placed their stick and bottle on it, and sat down. They drew their knees up to their chest and hugged them. Blinking slowly, Frisk just felt drowsy. They could see the sun set in the distance and was surprised to see that it was already evening.

I should have asked when she would come back… Maybe she is already here?

Their eyes widened and they stood up quickly. They sped through the forest, somehow not tripping for the second time that day. Frisk cursed themself for not thinking of that sooner. They needed to be at the entrance before she would notice, before her patience worn out, before she would get angry, before–

She wasn't even there.

Frisk was equally relieved and disappointed. No mom meant that there wouldn't be outrage and a critical lecture, but no mom also meant they couldn't go home and fall asleep on their bed. They were ready for a nap that would last until the next day. It took them a long moment to realize they left their stick and water bottle behind.

Nighttime had fallen with Frisk still at the entrance, waiting with their stick and bottle. With their droopy eyelids and small frown, they almost looked too apathetic for someone in their situation, but Frisk was holding all of their distress in. A pit grew in their stomach, deep enough to make them feel sick. Their hunger didn't help matters much. Whispers deep in their mind told Frisk that normal kids wouldn't have something like this happen to them.

They wrapped their arms around their body, and fell asleep shivering from the cold air.

Frisk woke up in the morning with the sun shining on their face.

Their stomach growled, and they bit their lip to stop themself from groaning. They reached for the water bottle and finished up what was left. At least they weren't thirsty anymore. Frisk felt extremely bad for littering, but they didn't know where else they could leave the empty bottle.

Feeling the need to move around their stiff joints, they took a hold of their stick and walked back into the forest. They didn't want to throw the stick away; something about holding it was comforting. As if it was keeping them grounded.

They wandered around aimlessly, not trying to go anywhere specific. They barely took notice of the unfamiliar landmarks, only focusing on their dread. They tried to think up excuses for why mom hadn't come yet. Maybe something was holding her up, maybe she simply forgot for now, maybe this was all a big joke. They eventually came to a disturbing conclusion in their dazed state, maybe their mother didn't want to deal with them anymore. To their embarrassment, they started to cry.

"Please don't leave me behind like this… mom…" They spoke through their sobs. Unreasonably, they hoped she would hear them and come out of nowhere with a uncharacteristically tender hug.

But nobody came to answer their call. Frisk hastily tried to wipe away their ongoing tears.

"Travelers who climb Mt. Ebott are said to disappear."

Like many of the children in town, Frisk was interested in Mt. Ebott. People often spoke of the disappearances around the mountain. The particularly strange elders talked about a legend where Monsters were sealed under the mountain because of their horrible actions against the humans. Not many people besides especially young children believed in it. Frisk was not one of them.

Frisk found themself walking to a part of the forest they never went to before. The ground got steeper as they continued on. The trees came to an end with an opening to a cave. They weren't sure if this was what they were looking for, but went inside anyway.

The cave had a surprisingly large hole right in the middle. Frisk stepped toward the edge and stared straight down. They tightened their grip on the stick, and felt oddly calm.

This was for the best.

I doubt that this is the only fanfiction about why Frisk climbed Mt. Ebott, but I wanted to try it out for myself as I had my own headcanons about it. I hope this was decent enough.

This is based on a post I saw around tumblr about the abandoned quiche you can find and how it might relate to Frisk's backstory.