Now, first things first. Spoiler warning. I will mercilessly spoil anything in Adventure Time from Season 1 to the most recent episode at any given time. I will spoil everything from Undertale, ever. If you have not finished Undertale completely, nor are caught up on Adventure Time, then you have been warned. These spoilers start from word one, as well.

Now, I know what those of you coming from 'The World of Dragons' are thinking. You're thinking I'm crazy, starting another story so soon after I started my first. But the thing is, I've been sitting on this first chapter for a couple of months. From January until almost May, I didn't even think I was ever going to actually work up the motivation to keep researching games for that other story. Thus, I started something smaller with only works I'm very familiar with. And so, It Changes was born.

I don't have much of a plan for this story, after the beginning arc. I don't want one, either. It's a merging of two things I love, and that's it. It will be something to write when I'm not trying to finish a jigsaw puzzle using thirty different puzzle sets, so to speak.

Disclaimer and rambling aside, I hope you enjoy this short introduction.

Chapter 1: The Kid in the Striped Shirt

It wasn't a sudden decision. She'd thought all day on it. No, she wouldn't let anything happen. No one would die today if she could help it. All she had to do was move a little faster. The cold of the snow on her bare feet would've been painful if she had anything left in her to focus on it. As it was, every ounce of her willpower was bent to make her move. She could see the lights from buildings ahead of her. A town? There hasn't been one out here before, had there...?

She ran past a welcoming banner, proudly welcoming any and all into 'Snowdin' without sparing it a glance. The monsters around her gave her curious stares, but she didn't have the time to dwell on them. One particularly loud monster shouted after her, but she didn't listen. Just as fast she had entered the town, she had left it. The familiar sight of bright crystals lit her way through a sudden fog and out of the snow.

The smooth stone of the area she remembered as Waterfall was easier to walk on than snow, but the water made up for it. She came to a gap where she could see a very small bird on the opposite side. She swam across, and the bird stared at her in amazement. She paid it no mind. She ran around another small pool, not noticing nor caring for the vague outlines of houses down the side passages.

As she moved, she came across a dark room. Her palm lit up with fire magic, and she bypassed light-up mushrooms and crystal-lit lanterns alike. The tunnel opened up to the large 'room' that made up most of the Underground. She could see the castle in the distance, but under it she saw another opening. The maw of rock seemed to be trying to threaten her, but she didn't have time to be afraid. She didn't have the time to acknowledge increasingly moist air as she passed through the maw.

A mechanical sign brightened the next craggy corridor, proudly proclaiming 'Welcome to Hotland.' The ancient memory of when she was last here nearly gave her pause, but she pushed onward anyway. She passed the sentry station with snow on its roof onto the bridge which held sturdily far above the molten heat below her. She turned away from the metallic structure to the spire. She stepped into the elevator. A digital sign above the door told her she was on L1.

The elevator was new, so she hazarded a guess as to where she needed to go. She pressed L3. The sound of elevator's ascent whirred around her. She tapped her foot impatiently, hoping that any motion would keep her from realizing how tired she was. Her feet were moving as soon as the whirring stopped. She slid through the just barely open door, and moved around a chubby-looking skeleton who she assumed to be waiting for the elevator. She didn't notice the sign lit up with R3.

She ran up a flight of stairs and came upon a resort of some sort. Seeing no way around it, she rushed through the doors. The sight of the fountain gave her pause. It was wrong. The statue at its head should've been...

She shook her head and passed around it. No time. She overheard a slime angrily and loudly complaining about the elevator not working. She saw an exit in the back of the resort. She'd have to find another way then.

She found another elevator. She took it to the only other options, labeled 'the end.' Convenient, since the facility hadn't been around when she left. She'd have been lost. The elevator opened. She willed her screaming feet to hold out. She moved and came across yet another elevator. She pressed the option that said 'New Home.'

Whirring. Whirring. Whirring.

It went on for eternity. The universe taunted her with these accursed elevators. It left her time to think, and she didn't want that time. Time to think of the child, dead before the king. To think of their battered body. To think of the king as he gathered the seventh soul, and turned into a god. That man certainly couldn't handle the power.

She was far more scared to consider the alternative.

She'd resolved that no one would die if she could help it.

The door opened. She ran through the streets. She came upon that house. It hadn't seemed to age a day. Even the flowers outside seemed the same, if not brighter. She entered the house, as she knew the door would never be locked. At the top of the basement stairs laid a note.

'Howdy! I'm in the garden. If there's...'

She stopped reading. She ran down the stairs. Monsters lined the corridor. They gawked as she passed, but she still had no time to care. The whispers followed her down the hall all the same.

"The Queen has returned."

She exited the basement. She approached the castle. The great hall, with pillars standing tall on each side, greeted her when she entered. She passed through it. One last hallway, and she'd be there...

The throne room was empty, the floor was covered in golden flowers. She trampled them as she passed through. She couldn't help but spare a glance at the second throne, covered by a white sheet in the corner.

She could hear birds from the outside world. She could feel the fresh, clean air even down here. It must have been a beautiful day out.

It didn't much matter now. A featureless hallway laid behind the throne room. At the end was one last door. The barrier shone just as she remembered it to have always done. An illusion of grey light that did nothing to brighten it's surroundings. The only true light in the room came from a hole in the ceiling which shone the late evening light into the center of the room like a spotlight. Across the edge of the visible light was a large amount of dust, collectively spread by the wind and an hour's time.

"I just can't understand."

"What can't you understand?"

"I mean... Was this mountain always here?"

"Finn, sometimes you have to take what life gives you. You and I haven't done any adventuring or dungeon crawl in a while. Now that the unknown lays sprawled before us, you know what we have to do."

Finn Mertin the Human shrugged. He figured Jake had a something of a point. The last time they went into a dungeon was... Was it that train? Finn suspected it was the dungeon train. He shrugged at the memory.

Finn wore his normal trusted adventuring get-up. Animal hat, blue shirt, blue shorts, green backpack. He also had all the essentials with him. The needle of his blade of Grass stuck out of his hand, and the sword made from a copy of himself was sheathed on his back. He also had a compass so that they could still get home when they got lost. A flint... Steel... Trail mix... Bacon. Average adventuring gear.

"Whatever you say Jake," Finn said.

"It would be great if we found the mountain's secret soon though," Jake grumbled.

Finn could agree with that. The mountainside wasn't steep in the slightest this low down. The slight incline was still a killer on their feet two hours up it. But a mountain with this great of a pull had to have something nifty in it.

He knew why they were out here of course. Jake had seen the Cosmic Owl in his dream two nights earlier. Jake had dreamed that two of them had been walking somewhere he didn't recognize when what could only be an angel emerged from the ground before him.

'The cosmos has called out to me, Finn, and it is my duty to heed its call!' Jake had passionately declared when he told Finn the previous day. Finn had shrugged and acquiesced. He knew better than to argue against a sighting of the Owl. Well, except for that one time...

So they set off in a random direction not long after they awoke the next day. They left BMO in charge of the house and had asked Marceline to check in when she could. They journeyed around the Slime Kingdom, over hill and vale and found nothing of interest on the first day but a goat and a flower patch in a clearing. Jake was certain they'd find something, so when they woke up at around noon that day, thanks to Jake's oversleeping, they kept moving in the same direction. Finn guessed they could be going in the right direction, since the terrain was less and less familiar as they went.

Then they came to the mountain. They could see it from far off, and Finn had been hit by a wave of excitement. He didn't know this mountain. It was an inviting sight. The call of the unknown. Yet somehow it seemed familiar as well. Something definitely seemed off about the joint.

Was joint proper terminology for a mountain? Finn dismissed the thought quickly enough. No one would correct his language in his head.

Was this the place that Jake's dream needed them to be? It's not like it wouldn't come true if they got sidetracked. The magical, cosmic junk behind how the Cosmic Owl worked prevented that. They had plenty of time to search. After all, the Princess King of Ooo had fired them, so it's not like they had somewhere they needed to be.

Was that irresponsible? Probably, Finn figured. Still, BMO could take care of himself...

"Football!" BMO cried from within the world of the mirror. They watched as Football abandoned them, running out of the bathroom and closing the door. The only light left came from Dread filled the MO machine as they looked over their new prison. The mirror of the Treehouse's abandoned bathroom. Trapped by their closest friend. Maybe forever.

Would anyone notice they were gone? Football looked nearly identical to them, except for being flipped. Football sounded just like them too. What if Finn and Jake just thought it was a big game? Both of them had left the day before on a cosmic adventure.

No, BMO refused. He was a machine, but he had something most machines didn't have. They could feel just like they had a soul, and Moe had made them so that they were super creative. A series of emotions rushed through them. At the forefront of the emotional wave's wake was anger. Anger at Football's self-indulgent greed and his false promise. But where the metaphorical wave-of-emotion's anger would soak them, the crushing weight of determination would drench them.

BMO would be free.

...And Finn figured the Candy Kingdom wouldn't collapse beyond repair if they were gone for a few days. Even P. KOO couldn't mess up that much.

"Yo Jake, could you stretch above the trees and tell us how close to the top we are?" Finn asked.

"No can do, Finn. This is our journey to see through, no shortcuts," Jake answered sagely, his declination manifesting in his hand movements. Finn shrugged, having expected no less.

"You don't want to do it," Finn chuckled. "It's cool, bro."

"Hehe, you know it."

Finn put up a hand, quieting Jake instantly. The duo stopped where they stood, and listened. Finn listened with an intensity very unbecoming of him. His ears practically widened, and if he were capable of such a trick Finn would magically part the stitching of his animal hat from around his ears and quiet the light breeze surrounding them to better listen. Quickly catching on, Jake's ear literally grew larger, living out a piece of Finn's metaphor.

After a minute, the listening of a century brought nothing with it but nearly absolute silence. Only that light breeze caressing Finn's face and working itself into a piano whoosh through his hat. The concentration which overtook Finn's entire being brought another sense to his attention. Though the sound of the breeze told him nothing, he could feel a slight, comforting chill on it as well. It was a familiar type of chill, and Finn motioned forward. The duo's silence was at last rewarded as the breeze meshed with the sound of running water. Jake wore recognition on his face that Finn was sure he echoed.

After hours of trees, a small change in scenery was nice. They followed the sound of water until they found its source. The river before them wasn't very long, nor did it move very fast.

"We could probably swim across." Finn suggested.

"What, and get wet?" Jake asked. He shook his head. "Nuh uh. There's probably a bridge right around that way."

Finn looked downstream where Jake was pointing. He raised a curious eyebrow at Jake, quietly asking why he thought that. Jake gave a confident shrug, proudly and wordlessly announcing it was only a hunch. Finn returned with a 'eh, why not' shrug of his own. The river bent around the woods, seemingly to serve as a barrier that cut off the rest of the mountain. It was a peaceful beauty, but it also made Finn a bit uneasy. He couldn't shake off the feeling of familiarity emanating out of the place.

As Jake had predicted, an old looking bridge came into view just around the bend. Moss hung from its sides and years of erosion took even the grayness from the rocks beneath. Despite the wear, the bridge stood steadfast against the current beneath it.

"Um, Jake. Did you know that bridge was there?" Finn asked.

"Pft, of course I didn't! It was just an educated guess! With all the Deja vu I've been feeling this whole climb, I figured this itch in my bones had to be right," Jake responded. An idea lit up his face. "The itch of the cosmos. Maybe I saw it in my dream?"

"Huh. I've been getting hitting with Deja vu bombs all day too. Have we been here before?" Finn asked as they approached the bridge.

"I don't think so. We normally avoid the Slime Kingdom area." Jake answered. They stepped onto the bridge. Finn and Jake both jumped over a section of the brick near the center without thinking about it. It didn't look very stable there. The obstacle easily overcome, they were free to ascend the mountain once more. Finn looked back across the river at the sun. It would be getting dark again soon. They would need to stop and set up a campfire soon. It was getting chilly, and he told Jake as much.

"Phwoo, finally!" Jake fell forward onto his face immediately. A muttering came from where he lay, sounding vaguely like "'m roodie ooo oh ooo leap." Finn laughed. Typical Jake, he thought. He pushed his companion onto his side so that his face wasn't one with the ground. In protest, Jake stretched his face under his ear.

So Jake was caught in one of those states of tired then.

"Alright, fine. I'll get the firewood. You get some stones from the stream," Finn told Jake. It was a compromise, since Jake could do his part even without getting up. Jake sighed in a way that said 'fine, I'll do the bare minimum required of me.' Finn knew he'd do a little more than that just for his bro.

Finn followed the river upstream, hoping to find a landmark of some kind. Anything to make it easier for him to find his way back to the river. For all the nature surrounding him though, he wasn't having much luck. Trees, trees, and more trees. Not even a Lard roost in the river to go off of. With how dead the mountain seemed to be he was surprised to even see fish in the water. Something in the air itself seemed off. He couldn't figure out what kind of off it was. Most of his friends were 'off' too, that didn't make them bad peeps. Ice King maybe, when he wasn't behaving.

Was Simon a friend? Probably not, but Marceline liked him. Finn kinda pitied the guy.

Finn found a large clearing instead of his landmark. Figuring he could gather enough wood around the clearing, he set out his work. He also pocketed a few berries that he knew were safe to eat while he was there so that they wouldn't have to dip into their travel stash. If they found Jake's angel soon, they'd be able to indulge themselves on the way home.

As he gathered, however, he heard a noise from the trees. It was a soft sound. Finn placed down his sticks as silently as he could manage and crept toward the noise. He instinctually grabbed his sword, but didn't take it out. He tiptoed past the trees and over branches. As the sound got louder he recognized it as the sound of snoring. It came from opposite a large oak before him.

Plain brown laceless shoes came into view first. Blue sweatpants covers the figure's legs, and a pink and blue striped shirt overlapped it. The sleeping child slept in mild comfort under the tree, their hair a dark, disheveled mess and their face covered in bruises and dirt. Despite looking fresh from a rumble, the kid looked at peace.

Finn couldn't help but stare though. There was no doubt in his mind about it. He was looking at another human.

Well, he certainly didn't expect that today. Should he...? Eh, what the heck.

"Pst," he said softly. The kid didn't stir. They had to be a couple of years younger than him. Twelve, at the absolute oldest.

"Hey kid, you shouldn't be lying here, could you wake up?" He tried a little louder. The kid eyes closed hard and they shuffled a bit in place. Tired blue eyes opened up at Finn in what looked like minor annoyance. Probably for waking them up. "Yo, sup?"

The kid waved lazily at Finn before rubbing their eyes. They sat up and stretched out, causing a loud crack from their back. The kid covered a yawn with their hand before looking lazily up at Finn. The kid smiled at Finn now that they were a little more awake.

"Cmon, me and my bro Jake are setting up camp not far from here. You can join us if you want," Finn offered. The kid didn't even think about it before they nodded and started to stand. They nearly fell back down, but Finn caught them. "Careful there."

The kid nodded in acknowledgement, and with Finn helping them walking the two returned to the clearing. Finn told the kid he needed to carry his pile of sticks back, and asked if the kid could walk on their own. The kid answered by moving away from his support and taking a few experimental steps. Satisfied, Finn picked up his pile and they followed the river back.

The sunset painted the world in an orange filter by the time they arrived. Jake was resting next to a bunch of small rocks, already arranged enough to set the sticks in. Adjustments in the formation could easily be made if he needed to. The kid gave Finn a confused look and pointed at Jake.

"Yeah, that's my bro. I was adopted," Finn said casually. The kid fidgeted awkwardly a bit at the answer. "Don't worry about it. Dad was the best." Better than my actual dad could be, he thought. His thought remained unsaid.

The kid edged close to the campfire as Finn set the first sticks in. Satisfied with how many he'd put in, he was about to start to light it when he heard a grumble. The kid wore a sheepish look on their face. Finn pulled out the berries. He picked out a few that he knew to taste better uncooked, and passed them to the kid. They gratefully took them and dug in without question. Finn was sure Jake would understand.

"You know, you normally shouldn't eat berries you got from a stranger, kid," Finn said. "Who knows what someone would give you?"

The kid looked up long enough to shrug before they kept on eating.

"Oh, okay then. So..." Finn trailed off. He took off his backpack laid it beside him. He took out a piece of flint. "What were you doing up here?"

Finn struck his flint and sparks flew off, birthing the starts of the fire. He looked up to see the kid had stopped eating. They avoid Finn's curious gaze, taking a pointed interest in the river.

"Whatever, it's cool. I won't pry." Finn said. They were tired and hungry, so Finn figured they hadn't been having a good time. Last thing anyone needed then was a stranger bugging them. He'd ask again if thy hadn't left by morning. Although... "If you don't mind me asking, do you know where you're going? I haven't seen a lot of other humans around before. Only me and... Just me."

No need to talk about Martin. He took a twig and used it to adjust the firewood.

The kid shook their head. Finn wished they'd say anything at all. He couldn't even figure out if they were a boy or a girl. It was awkward.

"Do you have somewhere to go?"

The kid shook their head no. They squinted at the building fire. More satisfied with the size of the fire than the answer he received, Finn tossed the twig into the fire. He stabbed two more branches into ground opposite of a each other. He took out the berries that were better off cooked and stuck them onto a straighter stick. He twirled his hastily made spit over the fire.

"Do you know where you are?"

The kid considered the question for a moment. They sighed and shook their head. Finn carefully considered his next question as before speaking.

"I can't help you much there, I'm afraid. This is the first time my brother Jake and I have been out this far. If it helps, though, the Slime Kingdom is about half a day's walk in that direction," Finn told the kid, pointing his free hand across the bridge. The kid's face scrunched up in confusion. "I guess that doesn't help much then."

The kid gave a weak, apologetic smile. Finn sighed, and looked back to the spit. He hadn't noticed one of the berries was on fire. He carefully grabbed another twig and used it to scrape off the burnt vegetation. The kid was watching intently, an impressive feat considering they looked ready to pass back out. The promise of more food was probably the only thing keeping the kid awake.

"I don't think I ever introduced myself, did I?" Finn chuckled. He stood up and gave a small bow, keeping the spit pointed away from himself. From the depths of his being Finn mustered up the most exaggerated heroic voice, cleared his voice to make room for it, and he spoke. "Finn the Human, at your service."

The kid giggled. Finn sat back down and looked at the kid expectantly. The kid raised an eyebrow before realization sunk in with a mute oh. The silence made Finn uncomfortable. Was the kid mute? That'd be awkward, since he was trying to get them to talk.

"I'm Frisk," they said gently enough that he barely heard them. Finn smiled in satisfaction and a little bit of relief. He'd gotten them to speak, though he was still a bit disappointed that he still couldn't figure out their gender. It was really weird. Should he ask?

Nah, it'd be better if he didn't. That would also be pretty weird. He'd just keep thinking of Frisk as 'them.'

"Frisk huh? That's a cool name. The one sleeping is my bro, Jake. Speaking of..."

The smell of food awakened the beast. What had been peaceful breathes became a growing crescendo of sniffing. Jake's wide eyed and hungry face slid onto the back of his head. He stared intensely at the spit, now pulled away from the fire. More importantly, his eyes landed on the plumpest berry. He stared as if his eyes alone would will it into his stomach. In a sense, it did. Finn slid the berry in question off of the spit and flicked it towards him. Jake stretched his face forward with his mouth open wide and caught it.

"Food's not all done yet, but I knew you'd be up for first dibs," Finn said.

Frisk clapped at the display. Jake squinted at the sound of clapping. His face lowered until he could see the source of the sound. He jumped with his entire being when he saw them, and he sat up straight with his body parts normalized.

"Woah! Uh... Hey there?" Jake simultaneously said and asked. Frisk waved back casually. Jake gave Finn a confused look

"This is Frisk. I found them while I was out scavenging," Finn explained.

"Oh, cool. Sorry about that. You just startled me is all," Jake said. Frisk looked a bit guilty about that. "Aw, don't give me that look. You didn't mean to, did you little buddy?"

The kid hesitated for a moment as Jake finished speaking, but shook their head. Guilt was still painted on their tiny smile.

"Then don't worry about it! There's no use dwelling on made up problems," Jake reassured. Frisk seemed to be comforted by this.

"Feeling philosophical today, Jake?" Finn asked. He was holding a new spit with new berries over the fire.

"It's my dream, Finn. The Cosmic Owl's message has elevated my soul. I've gotta be spiritual."

Frisk raised an eyebrow at this new information, Finn noticed.

"You know about the Cosmic Owl, don't you Frisk?" He asked. They shook their head. "If he shows up in your dream, then that dream comes true. That's why we came out here. Jake-"

"Woah there, Finn," Jake interrupted. He moved close to Finn and whispered conspiratorially, "Are you sure we trust this kid. I mean, they look fine, but can we risk the angel's safety on looks?"

"Jake. For real? You know how weird and symbolic those dreams get sometimes. The angel could just be a neat flower, for all we know. Besides, I doubt that Frisk would be able to do anything as tired as they are right now," Finn whispered back. Jake didn't look satisfied, but didn't argue with him. That was lucky, because he wasn't entirely sure about that thing he just said. He was at a solid ninety percent sure that Jake's dream was a metaphor.

"Alright, I'm trusting you on this one, brother."

Finn smiled. He turned back to Frisk, only to find them curled up in a ball a short way from the fire. Light snores came from the child.

"Yo, Jake, you'll still trust me on this one in the morning, right?"

"I'm too tired to change my mind again right now," Jake answered.

The sound of the river mixed with the crackling melody of the fire. Finn would sleep comfortably that night, knowing he'd finished his explanation to Frisk in the morning. Finn and Jake would probably have to start going back home when they got up the next morning. They'd bring Frisk with them, probably. Finn would feel terrible leaving a kid alone with no where to go. Ooo had some nasty beeswax out there.

And he'd been there before, anyway.

And he fell asleep, unaware that less than a mile from where he slept an entire people found that their king died, alongside the hopes and dreams he carried with him.

I warned you about spoilers. Already name dropping Frisk in chapter one, plus I told the Adventure Time watchers exactly what episode I'm calling the starting point. This starts in Season 7, man! With six really long seasons behind it! Consider this your final warning.

I've also just gotta say that writing Jake's dialogue is wonderful. Trying to describe his movements much more difficult. I'd been writing fluid, realistic movements on fictional characters for months, so having to come up with descriptions for Jake's stretching is surreal.

Any and all criticisms are welcome!

Update 6/01/16: fixed a few odd sentences and errors that I caught on a re-read. There are probably more in there, but I didn't see them. Also removed my note about not updating this often, since this is getting a bit of attention. I was expecting one or two people to like this and I've gotten a few more than that on an intro chapter alone.