This story is a prequel to my "Once Upon A Handplate" fanfic. But it also works as a normal fan-prequel for "Undertale" too. This is basically a short story of what made Frisk climb up the Mount Ebott. It's basically a bit of backstory of my Frisk.

I don't own "Undertale" or its characters. They belong to Toby Fox. I only own Frisk's biological mom.

A seven years old girl was lying in her bed beneath the covers, listening to the bed time reading by her mother. At some point, the woman dogeared the page of the book, to remember where she stopped to resume the reading the next evening.
"Aw, you stop already?" - the little girl asked her mother with disappointement - "Just when it all got interesting…"
"Sorry Frisk, but we're already fifteen minutes past your bed time." - the mother replied, as she put the book back on the bookshelf.
"I really wanna know what happens next…" - Frisk pouted.
Francesca looked at her daughter with an amused smile, then stroked Frisk's head in affection.
"Well, it gives you something to look forward." - she pointed out, then asked - "But if you're so curious, why don't you read the book all by yourself? You can read just fine."
"I just like when you read to me." - Frisk replied with a large grin - "Stories sound nice with your voice."
It was true. Being seven years old, Frisk could read well, but she just liked when it was her mom who read to her. Francesca had a gentle and soothing voice. A very motherly one, to put it differently. And so, every time she'd read a book, Frisk would get very caught by it.
"Mom?" - the girl asked, a question suddenly crossing her mind.
"Yes, Frisk?" - Francesca asked back.
"There's always lots of magic in the books you read me… So is magic real?"
Francesca was surprised by the question, but smiled. It wasn't an easy question to answer to, especially that the opinion on the matter were all pretty different. However, if magic was something that caught Frisk's interest, Francesca thought that she'd provide an answer as complete as she could. After all... herself she could never really abandon her own fascination for it.
"It's more than likely that long time ago, magic did exist in our world." - the mother answered - "But since it was a very long time ago, magic's seen just as myths and legends."
"So... people just forgot about magic?" - Frisk asked, getting a nod from her mom - "That's why it's not here anymore? Because they don't believe in it?"
"...You can put it that way, yes."
Frisk grew thoughtful for a moment, as though not fully satisfied with the answer. But then her face lit up and she asked another question.
"Then is there a place where magic still exists?"
Another difficult question. But Francesca didn't mind a single bit to talk about it. It must've been years since she's last talked about magic or other legends with anyone. Now that Frisk asked those questions, the woman felt like she was years younger.
"I think it's not impossible." - Francesca answered honestly - "Yes, I believe there's still a place where magic might exist."
"Oh? Where is it? Where is it?" - Frisk asked, sitting upwards.
The little girl's brown eyes were sparkling in excitement, which made her amused mother chuckle.
"Remember the story about the war between humans and monsters I told you? That monsters all had magic powers?" - the woman asked, making kid nodded in response - "Well, legends claim that wizards banished monsters underground, beneath a mountain. This mountain is the one we call Mount Ebott nowadays. So if magic does still exist somewhere, it would be beneath the Mount Ebott."
"Really? Then why don't we go there and see?" - Frisk asked, growing more excited - "The mountain's not very far from here!"
"Your enthousiasm's endearing, but people prefer to keep distances from that mountain." - Francesca stroked her daughter's hair fringe - "It's not safe to go there."
"Why not?"
"Because a few people seem to have climbed the mountain before... but they never returned." - the mother replied - "They went missing to never be heard of again."
"Oh... That's sad." - Frisk looked down in disappointement, but then her face lit up again a little - "But... But what if they never returned because down here it was just so wonderful that they never wanted to leave? It's a possibility, right? A world full of magic can only be amazing."
"Oh, Frisk... You're such a dreamer." - her mother ruffled Frisk's hair - "Alright, it really is time to sleep now. Goodnight, Frisk."
"Goodnight, Mom." - the girl hugged her mother - "Love you."
"I love you too. Sleep well."
With those words, Francesca pulled away and turned off the light in the bedroom before leaving. Frisk turned on her side to face the wall where phosphorescent stars and moon were glowing in the dark. As she stared at the green lights, her mind was filled with what she and her mom just talked about. The idea of a world full of magic and people that looked different sounded just so awesome! Frisk grew curious to learn more about those "monsters" legends told about. She decided she'd ask her mother the next day. With a determined smile, Frisk closed her eyes and soon fell asleep.

Five years later...

Many things have changed since the night when Francesca told her daughter about monsters, magic, and the legend of Mount Ebott. The little Frisk grew in height, being a young pre-teen. But with good changes came the bad ones. Frisk also became an orphan, since her mother was no longer part of this world. It took her a lot of time to heal from the loss, and the transmitted fascination for the old legends partially helped her in this. Because even though Francesca was gone, Frisk still had a part of her that she could hold into and that couldn't be taken away in any way. Despite the warning about people never returning from Mount Ebott, Frisk was still very curious about the world beneath the mountain. Not a day passed without her wondering how it was like. Her schoolmates found it silly that she'd dream at her age about something that (to their belief) didn't exist, but Frisk just couldn't help it. In the human world, everything was pretty much the same and unchanging. In Frisk's opinion, magic would add a bit of spice to the daily life and make things more interesting. What if it was possible to manipulate the natural elements by the single power of will? What if animals could walk and talk like people? What if it was possible to cure injuries in one instant? There were too many possibilities of defying the established human logic of things. Unlike humankind, monsters were so very diverse! "Aren't they tired to know all the same things?" - the girl would ask herself - "Don't they think magic is wonderful? Why banishing the monsters under the ground just for being a bit different? Being different doesn't make one bad, right?" As Frisk grew older, she realized that magic was maybe the exact reason why a war broke between the two races. And she couldn't understand it. This made her want to see the monsters - providing they were still alive down there - by herself. She couldn't see how something so magically fascinating could've scared her kind so much. People liked fairytales, so why would they dislike actual magic? Those were the thoughts that led Frisk to go investigate closer on the matter.
And thus, here she was now standing near the mountain, looking up at its peak. For some time now, Frisk had for ritual every friday after school to go near the mountain. She'd walk around, enjoy the silence of the surrounding forest and relive the memories of the stories her mother used to tell when she was still alive. The very first time, Frisk was a bit anxious to get so close to Mount Ebott. But her heart would drive her only closer. And so, she returned the next week. And then again. And again. Her heart would flutter every time. It was as though the mountain was calling for her. It attracted her with an invisible force like a magnet. Every time, Frisk would thus go closer, eventually climbing a little higher. Last time, she climbed high enough to level the pine tips of the surrounding forest. Frisk knew it was foolish and dangerous. People never returned after trying to explore. But she couldn't help but follow that call from her heart. And said call only grew stronger every time. Besides, every time she had returned, and it was enough to convince her to go there again the next week.
"Today, I shall climb to the very peak." - Frisk suddenly made up her mind.
As soon as she thought that, she felt a wave of determination in her whole being. That day, she had to make a bigger step. She came pretty far last time, so she could handle a climbing to the peak. How bad could that be? All she had to do was to be careful... As she was climbing higher and higher, Frisk could feel her heartbeat fasten in excitement. She's never been so close to that famous world of monsters. "Just a little peek..." - Frisk thought - "A little peek and then I'm going away." Frisk knew reasonably that she could never go just visit that other world. But if she could have just a small glance of what it may be like down here...
And soon, Frisk she made it. She was at the very top of the mountain at a few steps from a large pit. "I'm on the top of the mountain... I'm there! I'm finally there!" - Frisk thought as her eyes shone in excitement. Then, she jumped with her fist in the air, yelling with everything she had in her chest:
"I did it!"
Then, she calmed down, remembering how unsafe it was up there, but her heart was beating as madly as seconds ago. Never has she been so close to the world she dreamed so much about! After inhaling deeply and exhaling longly several times, Frisk decided to walk a bit closer to the hole and look down. "Just a little peek." - she reminded herself again. As she sat near the edge of the hole and held firmly into the earth and leaves, Frisk looked down. She bowed her head very slightly, to see or hear anything from what was beneath the mountain. But all her eyes met was darkness. The mountain was way too high to see anything that was down under. No sound came either from, the hole emitting nothing but silence. Frisk guessed that the way to reach the underground was a very long one, and that jumping in that hole would be a very bad idea. "That's a bummer." - she then thought - "I hoped I could see at least a little something from that other world." Frisk didn't know what exactly she expected, but she guessed that it wasn't something very rational. "Am I really just a desperate dreamer?" - the girl asked herself - "Maybe there really is nothing down here? But if people disappeared without ever returning, it can't be for nothing!" As she kept staring down the hole, she mused: "Whether or not there's a world of monsters beneath this mountain, I can't stay here." It was true. Even if she had actually seen something, Frisk couldn't just purposely jump in the hole. That would be a very foolish thing to do. Even for a dreamer like her. At least, she got this close to the other world. With a sigh, as Frisk proceeded to carefully stand up, she muttered to herself:
"I shall go, before an accident ha-AAAHH!"
An accident did happen, just like Frisk feared. As she tried to stand up, she slipped and almost fell down. The tween still held into the edge of the hole, hoping to make it back on the surface. But no matter how much she kicked her legs, she just couldn't find anything as backing. Frisk felt how her hands were giving up, and it made her face grew pale in alarm.
"No, no, no, no, NO!"
And then, her hands lost their grip on the earth. Frisk felt herself fall down the hole at a high speed, her heart pounded painfully against her ribcage, and all she could do was to let out a loud yell.
"AAAAAAAAAHHHHHHH!"
Frisk's last thought was how she didn't want to die just yet, before her world grew black.

A round light from far above was the first thing Frisk saw when she finally opened her eyes. At first, she was confused but then quickly recalled what happened earlier. She had climbed on the peak of Mount Ebott, and then… Her head and limbs sore, Frisk slowly sat down with a moan, while trying to process. As she rubbed the back of her head, the first thing she understood was that she was alive.
"I'm alive..." - she breathed out - "I'm alive..! But how..?"
Considering the height of the mountain, her survival was a freaking miracle. Frisk was certain that she would die before losing consciousness. And yet, here she was alive and well. Frisk then realized that she was sitting on something soft. She looked down and saw that it was a bed of golden flowers. "They must've cushioned my fall..." - she thought. Never would she think that she'd be so grateful to some flowers. Frisk then slowly stood up on her feet and looked around her. Another important realization hit her, besides the fact that she made it alive after the fall. She was now under the ground, all alone.
"Hello..?" - she called out - "Is... Is anyone here..? Anybody?!"
But nobody came to her call. Fear quickly replaced relief and the girl started to look around her almost frantically. This was what she got for being too curious! Besides the spot where the flowers grew illuminated by the sun, everything around her was dark. But after Frisk stepped off the flowers and when her eyes adjusted to the dark, she spotted something that resembled a gate. Curious. This calmed her a little bit, and she came up with a logical thought: "I fell in the underground... But if there's a way in, there surely must be a way out." And so, feeling her determination returning, Frisk limped to the gate. She didn't waste time to cross it. On the other side, she was met by a big surprise. In the middle of another dark room, there was a small illuminated spot with a single golden flower in its middle. A flower… with a face! But if the face already stunned Frisk, she was even less prepared to hear it talk!
"Howdy! I'm Flowey. Flowey the flower!" - the flower spoke up.
"Ah!" - Frisk let out a cry, backing up slightly.
"Hmmm... You're new to the Underground, aren'tcha?" - Flowey remarked after her reaction with a friendly smile - "Golly, you must be so confused. Someone ought to teach you how things work around here! I guess little old me will have to do. Ready? Here we go!"
Then, something surprising and confusing happened. Frisk saw a red heart start to glow on her chest, making her gasp in surprise once more. As she stared at the heart with wide eyes, Flowey spoke again.
"See that heart? That is your SOUL, the very culmination of your being! Your SOUL starts off weak, but can grow strong if you gain a lot of LV." - he explained.
"LV..? What's LV?" - Frisk asked quietly in confusion.
"What's LV stand for? Why, LOVE, of course!" - Flowey answered with a joyful tone - "You want some LOVE, don't you? Don't worry, I'll share some with you!"
Frisk wasn't sure what he meant or what was going on, but guessed the flower must know better. After all, she was now in an unknown place, and some outside help was pretty welcome. Flowey then magically made appear something that resembled white pellets that floated between him and the girl in the air. Frisk looked amazed at the pellets as they were spinning around by themselves.
"Down here, LOVE is shared through..." - Flowey paused - "...little white... 'friendliness pellets.' Are you ready? Move around! Get as many as you can!"
Frisk didn't question it and did as Flowey asked. When the pellets flew in her direction, Frisk reached her hand to get some. But as soon as she made the contact with the flying objects, she felt a huge pain pierce her whole being.
"Argh!" - she yelped and fell on her knees.
She brought one hand to where her SOUL was, as she felt like her entire being was in pain. Frisk felt almost like she would faint at any moment. Panting, Frisk looked up at the flower, the question "why?" written on her face. This time, she wasn't met by a friendly smile, the only expression she's seen on the flower until now. No, this was a maniacal grin. Flowey actually looked scary, despite his small size.
"You idiot! In this world, it's kill or BE killed." - he said, his voice changing as well - "Why would ANYONE pass up an opportunity like this!"
The next moment, Frisk was surrounded by a circle of those "friendliness pellets", which then slowly flew straight at her. Frisk's eyes widened, her heartbeat quickened its pace once again, she felt sweat on her forehead... "This is it." - she thought in fear - "Now, it's really the end."
"Die." - Flowey said, before laughing maniacally.
As the scary laughter echoed in the room, Frisk braced herself expecting the painful impact to come. But it never came. All of sudden, a fireball appeared out of nowhere and flew straight at the flower. Frisk heard him gasp and saw him fly across the room. What happened? Where did that fire come from? Footsteps then got heard and Frisk braced herself again, fearing what was coming next. The footsteps stopped and then... a voice that sounded very familiar spoke up.
"What a terrible creature, torturing such a poor, innocent youth."
Frisk froze. She'd know that kind, gentle, motherly voice anywhere. Her heart skipped a beat. "Mom...?" - she thought to herself. The girl then dared to look up, to see who just came to her rescue. It was a white goat-person with brown eyes, dressed in a purple dress with a strange symbol sewed on the front. "Silly Frisk. Of course it couldn't have been Mom." - Frisk mentally told herself - "She died three years ago." The female goat monster looked down at the human girl and knelt down, reaching her hand. Frisk instinctively flinched a little, not sure what to make of that person. The goat monster spoke up with her usual gentle and soothing voice:
"Ah, do not be afraid, my child."
As she said that, she gently laid her hand over Frisk's head to put the girl at ease, then her furry hand glowed green and all the pain that Frisk felt in her body and SOUL was gone in one instant. Frisk was surprised by the sudden disappearance of her injuries, but guessed that she's just been magically healed. Finding the courage to look at the goat-person again, she did just that. Meeting the girl's curious eyes, the monster smiled and introduced herself.
"I am Toriel, caretaker of the Ruins." - she said with a smile, eliciting from Frisk a weak smile of her own - "I pass through this place every day to see if anyone has fallen down."
This statement caught Frisk's attention and recalled about the rumors concerning the mountain.
"So people did fall in here before..?" - she asked.
"You are the first human to come here in a long time." - Toriel answered with a light nod, then offered her hand to help Frisk up - "Come! I will guide you through the catacombs."
Shyly, Frisk accepted the offered hand and noted how pleasant and soft it felt. The red heart on Frisk's chest then disappeared out of sight. The girl stood up and Toriel once again smiled kindly at her. This time, Frisk responded with a much bigger and happier smile. Somehow, this goat woman put her at ease and made her feel safe. Her voice undeniably played a part in it. It resembled so much the voice of Frisk's deceased mother... As for the rest, Toriel obviously didn't resemble Francesca at all. It was the same as comparing an apple and an orange. And yet, Toriel's brown eyes reflected the same kindness and motherly nature. Frisk thought that if there was someone she could entrust her life to down here, it would be Toriel. The goat monster then moved her hand in the direction of another gate behind her, as though displaying it.
"This way." - she said with a smile.
Toriel then turned around and walked to the door, not without looking back at the human child. Frisk gladly took Toriel's inviation to follow her, and so she gladly caught up to her in no time.
On the other side of the gate, Frisk's eyes widened when she saw the room she just wallked in. It was a beautiful ancient hall with purple walls, white columns, climbing plants and red dead leaves lying on the floor. The latter intrigued Frisk, considering it was spring and thus leaves couldn't fall from trees just yet. "Maybe things work differently down here?" - Frisk guessed. It was only then that it fully occured to Frisk what she just experienced. She fell down the hole of Mount Ebott, and ended in the land where monsters lived! She's been attacked by a talking flower, rescued by a goat-like person, magically healed and - the most incredibly - she could see her own SOUL! The latter was really something she never imagined in her wildest fantasies. "I'm in the world of monsters, the magical beings..." - Frisk mentally said to herself - "Now you really did it." With a smile, she started to walk across the ancient room. Frisk guessed that it was an appropriate scenary for a place populated by creatures with magic. The hall was almost like those from pictures in her old books. Toriel had already gone upstairs and waited patiently near the door for the child to admire the scenary. She looked at the girl with a smile, glad that the human didn't seem too scared or uncomfortable. Maybe she'd stay without a fuss, Toriel thought with a smile. Frisk then looked up and decided it was time to join this kind woman. This new world could be either a nice place, or a dangerous one. But whatever it had to display, Frisk was eager to discover it.
The shadow of the ruins loomed above, filling her with determination.

A/N: After long thinking, I decided that Frisk's mother's name should be Francesca, just like was Frisk's name during the De-Code. I thought it was nice, like she'd have a small reminder of her mother during her false life. This idea came from once again and obviously from the tv show "Once Upon A Time", where Snow White's cursed name is Mary Margaret, a name that came from the time she introduced herself to Red Riding Hood as Margaret, then as Mary.

As you can see, Frisk got her interest in magic and other fantasy-like things from her mother. The stories told by her mother really picked the girl's curiousity and made her ask herself: "What if those stories are all true?" A world filled with magic and creatures looking different from humans was very appealing to her, and Frisk held into the idea even more when her mother died. And we all know the final result of this obsession. XD
This is basically one of the reasons I see Frisk as a girl. Personality-wise, I picture them to be like a modern Alice or Dorothy. If you think about it, when a story has a protagonist ending up in a magical world, the said protagonist is usually a girl. Alice from "Alice in Wonderland", Dorothy from "The Wizard of Oz", Sarah from "The Labyrinth"... those are the most famous examples! So, when you have a game like "Undertale" that features a child travelling across a strange land full of monsters and magic, difficult to not associate it with those stories! :D And so, I decided to give my Frisk a bit of Alice/Dorothy's vibes, by making her dream about a place that's not like the human world.

I love the idea of Toriel and Frisk's real mother having similar voices, and perhaps even some tastes and interests. I like to imagine that if I was a movie director and that if I made a live Undertale movie, I would've made Frisk's mother and Toriel be portrayed by the same actress. ^^ The same voice would help Frisk to bound with Toriel and see her as her own mom.