Eight-year-old Okumura Rin walked leisurely up the mountain, mind running wild with the legends this particular mount had. It was said that nobody who climbed Mount Ebbot returned ever again. How someone had thought this place was a good idea for a class trip was beyond him.

He did have to admit, the mount itself was peaceful. At least Yukio seemed like he was having fun, for once nobody bullying him for either his intelligence or his crybaby status. Oh no. The second the class had been told about the supposed 'legend' that involved the mountain -monsters being trapped underground- heads had been turned to him, communicating their desire in whispered claims.

Demon child.

Monster.

You should be down there too.

To his credit, Yukio looked upset for the choice of words- Rin sped up after brushing off some leaves of his blue-and-purple striped sweater- but he didn't say anything. Rin didn't blame him. They were an unlikely pair- the demon child and the brightest of the class- even if they tended to be shunned for it. Rin didn't exactly enjoy that. That was the reason why he didn't like school. He wanted to go away, change his name and go to a different school, one where nobody would know of Okumura Rin, the demon child.

Which brought him to this moment. He had only intended to go on his own for a bit, to get away from all the noise, but the looming rock formation above, standing tall and proud...it was an open invitation, really. It would be only for a while. Neither the Sensei or Yukio would notice. He just wanted some peace and quie-

Woah.

A large, dark hole was spread out before him, almost like a void to some unknown realm, beckoning the light to be absorbed. Carefully, Rin picked up a nearby stone, walked up to the edge and threw it in. He did not hear it hit the bottom.

"Rin-Nii-san, don't!" a high pitched voice called from behind, rapid footsteps following. Thumpthumpthump...

The aforementioned child turned around, finally catching sight of his little brother rushing towards him as quickly as his legs would carry him, panicked tears behind his glasses and staining his green and yellow sweater. The thought of his Nii-san falling down there made all rational thought fly from Okumura Yukio's head. Rin held his hands on a placating manner, intending to tell the glasses-clad child that jumping over the edge had never been their intention, or would have if Yukio had lost his momentum.

Rin watched as, very near him, his twin brother's shoe caught on a vine, and he tumbled forward, both boys colliding. Desperately, they reached out one last time, brushing their fingers together...

Yukio was pretty sure his mind had broken when he felt soil beneath his fingers. A strong smell of flowers permeated his nose. If they had died, and when a person dies their souls go back to Gehenna, then the mirror dimension wasn't as bad as Yukio thought. He registered the smell and realized that, surprise surprise, he was still feeling. His sea green eyes opened fully, and the first thing he saw was a pinprick of light. How was he still alive? Falling from that distance would usually have spelled certain death both for him and Nii-san, so why...

...

...

...

..

.

Nii-san!

Slowly, Yukio managed to pull himself upright. It took a few moments before he felt steady enough on his feet before he looked around at his surroundings. Traces of sunlight barely managed to filter in through the small cracks in the mouth of the cavern. Rin-Nii-san was alive and sitting, thank God, and was slowly twirling a flower between his fingers, a bored expression on his face.

Then Rin looked around and spotted his brother. "You're awake, Kio! I thought we were goners for sure, but those," he slowed the flower in his hand. "Broke our fall!" But did they break their fall? Or was it them calling both twins to trip up? Otherwise, there was nothing but darkness circling them. Oh, and a destroyed pillar.

The navy-haired boy scratched his head. Hell certainly looked odd. He actually expected more fire and brimstone, not a tiny place filled with flowers. With Yukio awake, and relatively unharmed, he decided the best thing to do was to start walking.

"Kio, can you walk?" he asked, absentmindedly putting the flower beneath his ear, with half a mind to give it to his Tou-san as to lessen the scold that would sure befall him once they're out of there.

The affirmative given by the younger of the two was what made them start their journey. They walked hand in hand, feeling the walls to guide them and carefully moving their feet to avoid stepping on stray stones. Their eyes were wide open, but it didn't do much good on a place where the only source of natural light had been regretfully left behind.

But then, they saw it. A small, dim light, highlighting a lone flower in the midst of a barren space. The twins saw a path behind it, and knew they would have to follow it, to try and find an exit from...whenever they were.

But then, the flower turned around and looked at them.

...Wait.

Flowers weren't supposed to have a face.

A demon?! was Yukio's startled thought the second he laid eyes on it, but judging by his elder brother's yelp, a demon it was not. Unless Rin had somehow gained the ability to see them, but it was unlikely.

"Howdy!" the flower cheerfully greeted them, with Rin managing a shocked 'hi' in response. Yukio's reaction was not much better.

"You're a talking flower."

"Ye—"

"With a face. You're a talking flower with a face. You have teeth and eyes and—fangs? Why do you have fangs? How does that even work? Why does a flower have teeth? Do you have a digestive track? Or a skeleton? What would a flower's skeleton look like? ...And how can you talk? And what—?"

Yukio snapped his jaw shut as Rin lightly cuffed him behind the head. "Ssh, moley-four-eyes, the flower was talking."

"As I was saying..." the flower started up again, seemingly not bothered by the interruption. "Howdy. I'm Flowey. Flowey the flower," now it was Yukio's turn to subtly elbow Rin as he tried to muffle a snort. "You two must be lost."

"I'm Yukio."

"Where are we?" Rin asked.

"You've landed yourself in the Underground. A world of literal monsters." Flowey explained. Yukio nodded, relaxing a tad despite the description. At least this wasn't Gehenna.

"M-Monsters?" Rin blurted out, disbelief coloring his voice. Flowey nodded. "You're seriously expecting me to believe that?"

"Says the human listening to a talking flower."

"...Point taken."

"You two must be really confused, huh? Someone must teach you how things work around here." the flower proceeded to extend its two sepals, extending them wide and poking the two boys in their chest. Immediately Rin brought a hand to his chest, feeling pain blossoming, while Yukio groaned quietly. Awe filled two pairs of eyes as the areas where their hearts should be started glowing, which eventually shot out to their palm lever. The light had taken the stereotypical form of hearts. Yukio's was a bright purple while Rin's was a bright red and, oddly enough, upside-down.

Soon enough, what looked like four buttons flashed in front of each brother. FIGHT, ACT, ITEM and MERCY.

Yukio attempted to find the words to describe what was happening. "This...this is..."

Flowey smiled cheerfully. "Those are your SOULS, the very culmination of your beings," the elder sibling gasped in awe. Yukio frowned. "Wait, if those are our SOULS, how are we still alive?"

"Why are they of different colors, and why is mine upside down?" Rin asked with a confused look on his face. Flowey's smile dimmed a bit.

"SOULS come in a variety of colors. Red, for example, means that your defining feature, for now at least, is DETERMINATION. Purple means your feature is PERSEVERANCE. I have no idea why your SOUL is upside down, kid. And Yukio, this is just a manifestation of your SOUL." Flowey finished with the answers. "As I was saying, your SOUL starts off weak, but can grow strong if you gain a lot of LV!"

Yukio's stance immediately changed. "How do you gain LV? And what is LV?"

"Love, maybe?" Rin took a guess. Flowey giggled. "You're right, kid! You want some LOVE, don'tcha?" both kids nodded. "Don't worry, I'll share some with you." he released several pellets from the ground around it. "Down here, LOVE is shared through little white 'friendliness pellets'."

Yukio, however, had noticed Flowey looking to the side as he said that. His eyes narrowed in suspicion. "Nii-san, are you sure...?"

The pellets were already well on their way to touch their SOULS. "Ow!" Rin hissed and Yukio yelped in pain, hating that he was correct. Friendliness pellets=BAD. The flower's face had changed to something Yukio could only describe as 'demonic'. "You idiots. In this world, it's KILL or BE killed!"

Rin's eyes widened as he instinctively clung to Yukio. "Weren't you going to help us?!"

"What would I gain by helping you?!" the demonic flower screeched. "Why would ANYONE pass up an opportunity like this?" The twins watched as, to their horror, the bullets formed an unavoidable circle around them. "DIE!" Flowey screeched in a demonic tone. The pellets drew nearer dangerously quickly.

For the first time, the younger twin understood how love made someone capable of hate. Because he was going to die and Nii-san was going to die and there was nothing he could do about it. He wished he hadn't kept his guns at home, that way he could have showed the flower what real bullets looked like. If they survived the following minutes, nothing would stop him from plucking that flower and tearing every single petal.

Just before it reached them, the pellets went up in flames and were reduced to ashes. Flowey had a look of confusion on his face that was mirrored by the twins. A fireball came next, singing Flowey and knocking it away as it let out a pained yell. Yukio tensed for a moment, but it was quickly forgotten as a goat wearing a dress walked into the room with the posture and dignity of a queen. "What a terrible creature, torturing such poor, innocent youths." she said.

Rin put himself in front of Yukio as the goat woman came closer. "Do not be afraid, my children. I am Toriel, caretaker of the ruins. Would you like to come inside? I fear you might run into more monsters if you are here too long."

Yukio bristled at the invitation. If it were up to him, it would only be his Nii-san and him, but the flower was right. If they were to survive they would need allies. Preferably powerful ones.

"Please, as long as you are with me, you have my word that no harm will come upon you." Toriel insisted.

Deciding this decision was too important to be left solely up to him, Rin gestured for Yukio to come into a huddle.

"Should we?"

"It's either this or wait for the world's meanest weed to come back, Kio-touto-chan." Rin answered, a wide grin on his face at the end.

"You're right, Nii-san, it's our best option."

They broke up their huddle to face Toriel, their hands still clasped, a ward against the encroaching dark. "We've decided we'll go with you."

"...If you'll still take us?"

Without warning, two arms easily wrapped around them, pressing them against a chest that smelled strongly of butterscotch. The scent felt warm in their noses as the elder twin sank into the embrace, tired and hurt and still so trusting, still so willing to believe that Flowey was just a fluke, and they'd be able to make it in this world.

Yukio promised himself he would never be caught this off-guard by anything. No matter if it was even a demon puppy. He had to protect his sibling, and so he needed to be alert.

Heh. You remind me of myself, kid...

Well that was very worrisome.

The glasses-clad child shifted a bit in Toriel's embrace, who was already carrying them both. "I am Yukio." he wasn't prepared for what came next. The blue-haired boy seemed to think for a few seconds, before giving an answer Yukio had not expected.

"I call myself Frisk."

So this is my first Undertale fanfic...I hope I did the characters justice. Were the circumstances of why Rin changed his name clear enough?