Disclaimer and etc: I don't own Undertale, I only thought up the concept of this AU. The AU does not start at the beginning "technically", and the story starts off just like the game with Frisk falling into the Underground.

Things you should note: Frisk is 19 years old in this, but she's short for her age so she's still going to get called kid due to mainly shortness and striped shirt. Also, This is a Frisk/Sans story.

Also, the full name of this AU is Preset to Reset. Up to Chapter 14 of this story is posted on Archive of our own, but I'm going to get it caught up on here as well. I'm not posting the Preset part of the AU just yet. Preset focuses on Gaster and his story up to his fate when he falls in the CORE.

I think that's it. If you have any questions, comments or reviews. Let me know!

Frisk slowly opened her eyes, her hand grasping, the feeling of flowers in her hand made her blink as she looked around her.

Flowers…

So many golden flowers…

She winced while getting up, feeling around in the darkness outside of the light that touched those flowers. She could barely see anything from the path beyond them and looked at the small path that went straight. Her eyes went upwards, nearly opening her mouth she thought to yell before closing it again.

No, she needed to stay silent. Holding her hand to her chest, she winced at each step she took. The small path seemed long, her legs felt a sharp pain as she moved. Her hand fumbled to a wall, bracing herself as she pushed forward. She wheezed, falling forward once out the door. She clutched at her chest, breathing slowly.

"Howdy!"

She blinked, her eyes searching then looking down to see a small flower with a smile so warm and sweet, she'd think it was made of sugar.

Could someone be that nice?

She touched her head, wondering how hard she bumped it. Was this really one of the monsters of legend? She looked around it before a small wave, having no intentions of going anywhere near it. It smiled more, and a shiver went down her spine.

"I'm Flowey, Flowey the Flower!", He gave another smile, and Frisk started to scoot back from it.

No one could be this nice or act this happy…

Flowey introduced her to the underground, his smile never failing as he continued talking. Frisk watched him carefully until a tug at her chest caused her to shudder. Her eyes widened at the small thing as she clutched at her chest in refusal, her head shaking at the feeling of something being torn from her.

She was determined to keep it together, she held herself tight. Curling into a ball, wincing as the slight tugs became forceful pulls. She gasped for air, her chest feeling empty at the last pull.

She stared at the bright red, heart-shaped object in the air. It shined, pulling her close. The need of having it back nearly made her forget the flower, she glared at it. Its smile still wide, explaining that the jewel was her soul. Her mind went back, thinking of the surface and the books there before shaking the thoughts away.

She took deep breaths, hearing the Flower's suggestion before widening her eyes at what he said. He wanted her to run into the pellets? She shook her head refusing, slightly dodging as they came towards her while ignoring the pain shooting through her.

"Run. Into. The. Bullets!"

Frisk shuddered, moving again and was surprised to find herself to surrounded by the Flowey's bullet seeds. She looked around, trying to see a way out. A step to the left and right, only to find them closing in closer and closer. Her eyes narrowed at the Flower, his maniacal laughter echoed through the tunnel.

Then everything stopped, the area was clear and Frisk looked to see Flowey was just as confused. A warm feeling spread through her, green swirls covered her and she stiffened, wondering was this all a trick of Flowey's before she saw a ball of fire that caught Flowey.

Then he was gone. Frisk was sure he wasn't dead.

"Little one, are you alright?"

The voice was soft, yet echoed around Frisk. She took deep breaths, forcing herself to look in the direction of the sound, only to blink at the goat-like creature in front of her wearing a flowing purple dress.

"Such a horrid creature…" her eyes narrowed in the direction of where the flower once stood. Her eyes went back to Frisk, the warmth in them was inviting. "Here, let me help you." her hand went out, and Frisk stared at it.

"Oh! Pardon me, my manners. My name is Toriel, my child. I'm caretaker of the Ruins here in the Underground. "she smiled again, faltering as Frisk stared. "I promise, I'm not going to harm you. I come here to check and see if anyone else has fallen, it's been a long time since the last human fell." Frisk watched her get a faraway look, then focus back on her. "I already managed to heal most your wounds, but I fear I can only do so much from a distance. Come, I'll guide you through here, and you can rest easy."

Frisk turned to look behind her, nothing but darkness was there.

She looked back at Toriel, her hand shaking as she let her hand go to the older woman's hand. The softness of her white fur was warmer than Frisk thought it would be, it radiated heat. Toriel smiled at her, but it didn't do much to ease her fears as she stood, letting Toriel lead her once she was standing.

She followed closely, finding it hard to ignore the graceful way Toriel walked. She frowned at her own heavy ones, trying to keep up with Toriel's longer strides.

"I forgot to say, welcome to your new home" Toriel chuckled, but Frisk stiffened, pausing immediately.

My new home?

"Oh, hold on a moment." Toriel moved across some stepping stones, not noticing that Frisk had already stopped. Frisk watched a door open, the secret entrance made a shiver go down her spine at a distant memory. "The Ruins are full of these puzzles, but no worries. I'll teach you what you need to know, my child. Come now" she smiled, walking again through the door.

Frisk took a deep breath, thinking through her lack of choices before following if anything she could find a way out of here. The thought filled her with determination, the aura around her seemed to shift a moment as she paused again.

"My child?" Toriel's eyes went to her. Frisk was puzzled before following once again.

Frisk was confused when Toriel wanted her to do the puzzles herself, yet she supposed that was the best way to learn as they moved on to another room only to be confronted with a dummy. Toriel's smile was bright, urging her to talk to the thing made of stuffing and wood, she wondered was she serious. She wished for Frisk to avoid fighting, and this was an actual lesson.

Frisk decided to take it seriously, yet she was shaking. She felt nervous, the eyes on her as she mumbled softly to the dummy, "...hello" The dummy said nothing back yet Toriel's smile had gotten brighter, Frisk wondered if what she did was so amazing or great.

Toriel walked on, and Frisk followed, nearly jumping at the small beast that hopped around with green skin.

"It's merely a Froggit, my child" Toriel laughed softly, Frisk went a bit closer to it. "It's...pretty…" she murmured, the Froggit's head tilted. Its mouth upturned, in what Frisk thought was a smile before jumping back as the Froggit hopped towards her. Toriel cleared her throat, the Froggit turned its head towards her, and even Frisk feared the look on the woman's face as the Froggit ran for cover.

The rest of the way was quiet to the next puzzle, Frisk grabbed on tightly to Toriel at the sight of all the spikes on the floor. Her heart raced, her body shaking as Toriel rubbed her back. "Breathe, my child."

Frisk tried to, barely acknowledging Toriel's next words until hands were on her face and her eyes were wide.

"We made it through, see?" she smiled, and Frisk looked back, seeing that they did. She breathed in deeply, feeling a surge of courage rush through her. She looked back to see Toriel smiling and found herself looking at the floor, a soft smile threatening to come forth.

"But now, I want you to do something" Toriel's voice changed, making Frisk feel wary as she watched the expressions crossing on the woman's furry face. "I want you to try this path alone, forgive me but I know you can do it. "she patted Frisk's shoulder, alarms went off within Frisk as Toriel suddenly took off.

She…. she left?

Frisk stared, no longer seeing a trace of her anywhere. Her eyes went around, she was sure monsters were at every corner, and some were hiding like the little Whimsuns. The small things were more scared than she was, she looked back at the path, the feeling of betrayal hit first before anything else.

Hadn't she learned by now to trust no one?

She clenched her fists together, feeling a resolve to not only reach the end of the path but to leave altogether. Moving forth, the air seemed colder as monsters moved around her. She felt like she was being watched. The exit of the room was in sight before she knew it.

"My child, you did it!"

Frisk jumped, looking at Toriel's smiling face yet this time she looked at the floor not returning it. She saw Toriel's feet, then her head was tilted up to meet Toriel's face as the large goat monster crouched down.

"Young one, you realize...I was merely behind the pillar. I would never leave you."

"Okay…" Frisk's voice was quiet, she saw sadness spilling on Toriel's face, but she didn't know how to judge it. Was this another test for her to pass?

"My child…" Frisk's eyes locked on Toriel's. "I only wanted to test your independence, since I have some things to attend to, and for a small amount of time you'll be alone. You look, like a bright young woman. I never doubted you, I only wanted to make sure it would be okay to do this matter. I hope you understand now." Frisk merely nodded, thinking over the words as Toriel went quiet.

She stood, turning to leave then paused with a bright smile, grabbing both of Frisk's hands. "I have an idea. How about I give you a phone. That way if you need me, you only need to call. Sounds good?"

Frisk thought about it before nodding, soon a rectangular object was in her hands as she looked at it. It reminded her of something her mother would use back above ground, she bit her lip thinking of the woman. She needed to get back to the surface...quickly.

"Everything is okay, my child?"

Frisk looked away, nodding her head. The thought of telling Toriel to stop saying "my child" came to mind before dying away. The woman's voice was full of affection and life, would it be so wrong to let her have that. She wasn't happy with how she was left, but she could still tell there was a warmness to Toriel. She nodded again, wanting to quell her worries as Toriel squeezed one of her hands before leaving, and Frisk was left alone again.

The ruins were quieter now, and Frisk was inspecting her phone, eyeing the number that she knew would go to Toriel's. After some time, she finally called, if she would be with Toriel awhile, it seemed a good idea to at least know her.

Toriel was surprised, and Frisk could hear the happiness in her tone. The conversation was small with Toriel telling her only simple things. Once it was done, Frisk was left with the quiet again. She looked forward, wanting to go ahead as each minute passed.

After a few more minutes, Frisk started moving.

She was only a few feet in the next room as the phone rang with Toriel warning against exploration with how the Ruins were dangerous. Frisk didn't know what to say to that, her eyes looked around for a camera and wondered did monsters have those.

Or maybe they have…

She shook her head quickly, not wanting to complete the thought. Danger or not, she was already not where Toriel left her. Frisk looked around, the idea of staying still didn't appeal, she was determined to at least look around this place so she could figure out how to get home.

The shift in aura came and passed, this time Frisk ignored it as she set off.

She managed the puzzles on her own, also finding more Froggits who managed to teach her a bit more about the Underground. The biggest turning point had been meeting Nabstablook, a shy ghost who Frisk could tell needed a pick me up. She would have hugged the poor thing that seemed to think he was in the way, yet she wasn't sure how well that would go with a ghost.

Upon meeting a talking rock, she was shocked at not feeling any surprise at it. Her mind next went back to that Spider Bake Sale as she continued walking. The spider cider and spider donut in her hands were all she could afford, and she could faintly remember the words "of spiders" being an ingredient.

The oddest parts were Toriel's calls, every time she thought she may be found out yet instead the woman merely asked her questions, such as if she preferred butterscotch or cinnamon.

She stopped once she came to a tree, the leaves were all at the base. She could tell just by looking that anything that bloomed would fall off quickly, she frowned at the thought as her hand went to it.

"My child?"

Frisk jumped back, surprised to see Toriel so close and her cheeks heated up.

"I suppose I shouldn't be surprised, it took longer than I thought it would" Toriel laughed softly, and Frisk could remember a Froggit telling her how Toriel was buying groceries. "I shouldn't have left you alone so long, I'm sorry for that" Her eyes looked over Frisk. "Are you okay? You didn't get hurt I hope" Toriel frowned and Frisk quickly shook her head. "Oh, good. A surprise while you're injured, wouldn't be a happy one."

A surprise?

Frisk looked at Toriel confused, but she only laughed with a hand to her mouth.

"It's no point in hiding it longer, come" Toriel smiled, leading the way as Frisk followed her.