You voted and the majority wins: Fionna and Cake have a new fan fiction. That poll will still be up so if Finn and Jake end up taking the lead, I'll post a story about them later. Most likely a short story since this one is pretty long (or, at least, I hope it will be). I'm making this one a little darker than any other AT fic I've been writing.

And everyone has at least thought about, written fan fiction about, or drew about how Finn/Fionna are the last humans in the land of Ooo/Aaa. No, this is not a gender-cross. Just Fionna. So pardon me if I sound similar to everyone else but, rest assured, I'm not trying to copy anybody.

And for those of you who read my fanfic Bad Little Boy, you know that I take song requests of your own writing and put the song in my story, giving you credit of course. Again, I'm doing it. So if you have a song you want to submit, send me a PM or put the song in a review and I'll see what I can do.

Also: I know that Natasha Allegri had Cake be raised by Ice Queen but I'm having a hard time understanding how Fionna and Cake ended up ultimately meeting. So I'm keeping Ice Queen's relationship with Marshall Lee similar to Ice King and Marcy's, to make the story have a little more sense.

Disclaimer: Pendleton Ward owns and created Adventure Time. Natasha Allegri created Fionna and Cake.

The sky was black, thickened with the billowing smoke that congested the air. All that was heard were shouts of men and the shooting of guns as they advanced on the enemy. Women fighting their way through crowds to find their missing children, who were lost among the running legs of civilians, crying for someone to save them from this horror. Blood spattered the walls of crumbling buildings, explosions blasting behind soldiers making their ears fail for a few minutes and making them run in fear, unable to hear anything at all. Suddenly it became silent and a faint whistle was heard up above. It was getting louder, a zooming noise following it as it rocketed through the smokey sky. Chaos broke out as realization spread like a wild fire. Mothers grabbed their children and ran as fast as they could. Sometimes it wasn't even their own child. Men rushed forward, trying to out run the falling attack but it was impossible to escape.

Finally, the weapon shot for the ground and collided with the pavement, the Mushroom Bomb blasting every which way, killing thousands. Body parts flew across the scene and cries of pain were piercing the air.

Wake up!

Her blue eyes shot open and she sat upright, breathing hard in a cold sweat, hot tears running down her face. She leaned on the headboard and took in great gulps of air, trying to calm herself from yet another terrifying nightmare. Her blonde locks fell messily in front of her face and she brushed them away distractedly, attempting to forget the images that rushed through her mind's eye. A soft purr made her jump a little. Fionna looked over at Cake, who was still curled up in a little ball in her drawer, a pink blanket thrown over her furry body, her fluffy white and tan tail poking out and hanging over the side. Smiling in relief that she wasn't alone, Fionna closed her eyes and was able to calm herself with ease.

These dreams were getting worse and worse each night. The fact that she was considered the last human on the face of the planet and all of Aaa stirred a fear in her and gave her these dreams of the Great Mushroom War. Her stomach flipped over and she felt bile crawl to the back of her throat as more horrific images floated in and out of her mind. The blood, the crying children, the final drop of the bomb that eliminated everyone in its path, were all just too much for her. It was as if she was in the battle, looking around frantically for a place to hide, even though it was one thousand years before she was born.

Not being able to hold it in anymore, Fionna pounced out of bed and rushed into the bathroom and vomited into the toilet, sweating bullets and shaking violently. She gasped and coughed, her breath echoing into the bowl, waking Cake in the other room. Sleepily, the cat followed the sound of her sister's sobs of anguish and turned on the light switch that Fionna was unable to reach in time. For her seventeen years of life, Fionna had never looked so weak and helpless. Cake wandered over to Fionna and rubbed her back soothingly, letting the human cry over the dream, the trauma slowly dying away. Without a word, the feline cleaned Fionna up, wiped her mouth, flushed the toilet, and led her back to bed. Cake then slugged over to the kitchen, still half asleep, to fix Fionna a glass of cold water. Then she returned to her friend's side, making her drink the water until Fionna stopped shaking. Sloppy apologies slipped out of Fionna's mouth but Cake waved them away, not minding in the slightest that she had to get up to tend to her. It made her tired in the morning, it's true, but it wasn't like Cake would ever turn her back on Fionna. They did everything together and thus, if Fionna was up, Cake was up.

"You wanna talk about it, Honey?" Cake asked gently, handing Fionna another glass of water to avoid dehydration. After Fionna's little episode in the bathroom, it was important for her to consume a good amount of liquids.

"It's just the same old story," Fionna said quietly, sipping the water lightly, her hand still quivering. "Nothing new."

"I'm sorry you're having these dreams," Cake said. "I would stop them if I could, really, but I don't have that kind of power."

"Thanks for the condolences," Fionna said, putting down the water. "But I think they'll stop eventually."

"Fi, you've been dreaming the same garb for days. Ever since Gumball said it was impossible for humans to come back-"

Fionna planted her hands over her ears and shut her eyes tight, her childish ways still taking their sweet time to go away. "I don't wanna hear it!"

Smiling in spite of the situation, Cake dropped the subject and egged Fionna on to finish the water. Day break was peeking over the horizon so there was no point in going back to bed. The sky was painted with streaks of gold, pink, and orange, the sun rising higher and higher, wind picking up, making the grass wave across the many hills that covered Aaa and the clouds shift and glide through the sky. It was another glorious morning in the land of Aaa and it was blessing everyone who lived as the two girls started their day. Fionna pulled on her sky blue V-neck, slipped into her light blue mini-skirt, and leapt into her knee-high socks and black sneakers. Finally, she tucked her hair into her signature bunny hat, letting her bangs dangle out on one side. Cake had stretched herself down to the kitchen and began to stir them up a breakfast, humming to herself. Fionna put the nightmare in the back of her mind and raced down to meet her friend, ready for a hearty meal to start the day.

The bacon hit the pan with a sizzle and the intoxicating scent flittered up Fionna's nose. Her stomach growled and mouth watered, her mind forgetting her previous loss of stomach earlier that morning. After Cake finished prepping the greasy meat, she slapped some strips onto a plate for Fionna and some more on a plate for herself. The two girls sat at their booth together and began to dig into their breakfast. After the two of them washed the dishes, Fionna grabbed her green Adventure Pack and they trooped outside to journey to the Candy Kingdom to visit King Gumball.

Gumball, who was now twenty three (but certainly didn't look it), was the official ruler of the Candy Kingdom, dubbed king when he turned twenty. Even though he was a different title, his habits didn't change in the slightest. He was still the cooking scientist who experimented with baked goods, putting serums inside to test the effect when one eats the treat. He was still relatively the same height and his facial structure didn't change at all. The only slight difference was the fact that little gum stubble was starting to grow in places on his chin that actually made him a little more attractive. But teases from a certain Vampire King resolved in him shaving off the sweet facial hair before it overrode his face. He was currently awaiting the arrival of Fionna and Cake, pacing the floor and biting his tongue distractedly, twirling his pink thumbs and looking out the window to the perfect blue sky.

A knock at the door surprised him a little and he allowed entry. Fionna walked inside, Cake at her heels. Gumball paused for a moment to appreciate how much Fionna had grown. He wasn't in love with her in the slightest (although previous years showed he did genuinely care for her) but he enjoyed watching her grow up from a young girl to a young woman, even though Fionna hisses at the word "woman", believing that it was too formal and girly for her tastes. Still, in spite of that, she was no longer that fourteen year old girl who let her immaturity run wild. Her height still had yet to match Gumball's but was getting close, since her human body grew faster than Candy people. After taking in the beauty of human change, he smiled warmly, welcoming the two girls inside humbly.

"Hello, ladies," he said.

"Hello, your Majesty," Fionna giggled, bowing slightly, making Cake laugh too. Gumball sighed, knowing that Marshall Lee was certainly rubbing off on Fionna. "How may we serve thee this fine morning?" Fionna went on, straightening with a grin. It was hard to tell she had been crying that morning. It was as if nothing had happened.

"I was wondering if you could help me get something out of a dungeon today," Gumball said, striding up to them, his pink, royal slippers barely making a sound on the candy floor. "I've attempted to go inside but... it's far too dirty for me to go in." He smiled sheepishly. "I guess old habits die hard."

"They certainly do," Cake said, glancing at Fionna, who grinned knowingly at her. "But don't you worry, Sire. Fionna and I will get whatever it is you need."

"That's what I'm counting on. Now, it's a very simple thing to retrieve. A small chest that is said to hold some secrets I wish to decipher," Gumball explained to them, taking a map off a table and showing it to them. He pointed to a cave hidden in the depths of the forest. "If you don't mind getting it for me, I will be very grateful." He then closed the map and handed it over to Fionna.

"We're on the job!" Fionna promised, pumping her fist in the air.

"Mathematical!" Gumball said, grinning. "I'm counting on you."

Fionna and Cake bid him goodbye and retreated out of the Candy Kingdom, following the map to the cave. It was a dank, dark cave that was dripping with dew from the morning. Long, jagged rocks, that gave the appearance that the cave had fangs, stuck every which way in the entrance that Fionna made a mental note to avoid. Bushes and brambles were tangled in the "teeth" of the cave, making it even darker than it should be. It was hard to see inside so Fionna broke off a piece of tree to create a makeshift torch and sparked some rocks on the wood, making it burn bright to lead the way down the path Gumball was too neat to take. The girls wandered inside, taking care not to step on a rock or get caught in a spiderweb. Once or twice, the hissing of snakes startled them but they pressed on.

"Fi, this tunnel is taking forever," Cake said, sounding bored instead of frightened. "Where are the monsters or the goblins or something."

"Gumball only said it was dirty," Fionna reminded her from ahead. "He never said dangerous."

"His quests are getting boring," Cake determined. "I'm gonna have to have a word with him."

But Fionna stopped listening. A whistling noise, that was most likely the wind passing through, made her stomach preform a somersault. Gulping and starting to sweat a little, she remembered her dream and the whooshing sound of the bomb being dropped on those innocent humans. She stopped dead and felt her knees wobble, Cake accidentally bumping into her.

"Fionna?" Cake said, becoming worried. "Fionna? Are you all right?"

The words went in one ear and right out the other. The screams of the people filled her mind and the cries of children haunted her ear drums, her eyes going blind to everything except the many soldiers running and pointing up, shouting nonsense into the air. The whistling growing ever louder, the ground shaking from beneath her feet, her breath coming fast, and her eyes shutting in hopes that it was all just another dream. Two paws suddenly clutched her shoulders and shook her awake. Fionna was still standing in the cave, Cake's feline eyes glowing from the light of the fire Fionna was still holding.

"Wake up, Sugar!" Cake yelled, trying to snap some sense into her sister. "Can you hear me?"

"Y...yeah," Fionna croaked, clearing her throat and wiping her forehead of its sweat. She swallowed hard and pressed on, Cake at her side. "Sorry. It's just that dream just came back to me."

"If you're having these visions during the day, this must be bugging you a whole heck of a lot," Cake said, putting her paws on her hips. "When we get back to the Candy Kingdom, Gumball has some history to teach us about the Mushroom War."

"Cake, don't you know anything about the war?" Fionna asked.

"Not too much," the cat replied honestly. "But Gumball seems to know some so we can ask him. Hopefully that'll put your mind to rest about this whole business."

Fionna didn't respond. She kept on going until they came to the end of the path, a chink of light flooding down over a chest that was securely locked and chained. Fionna tenderly picked it up and the girls turned back to head over to Gumball and give him his chest. The journey back wasn't as hard to trek as it was going in. They came out a little grimier than before but didn't mind. Fionna hopped on Cake's back and the cat bounded towards the Candy Kingdom. They were then led upstairs to Gumball's location by Peppermint Maid and handed over the treasure to the king.

"Thank you, girls," Gumball said, unlocking the box with some sort of hard candy key. "How can I repay you?"

"By telling us about the Great Mushroom War," Cake said at once, ignoring Fionna's modest decline of a reward.

Gumball was slightly taken aback by this sudden demand. Fionna moaned behind her hand, which had moved to cover her face with embarrassment. Cake, however, was eyeing the king with an accusatory glare, slightly blaming him for Fionna's repeating nightmare. Gumball looked to the human for some explanation but she just shook her head at him. He then turned his eyes back on Cake, who was still expecting an answer.

"I'm sorry, Cake. But I don't know a lot about the war," Gumball said earnestly. Cake was skeptical so he said quickly, "I've read about it, sure, but it's all very fuzzy. The only known information about it is in the library but even those books are a little off on accuracy. It happened over one thousand years ago." He shrugged, still not completely meeting Cake's eyes. "The only two people who could possibly tell you about it with some truth are Ice Queen and Marshall Lee. But Ice Queen doesn't remember anything, according to those videos we watch every winter, so Marshall is your best bet."

A sinking feeling settled in the bottom of Fionna's stomach. Marshall was very touchy about the subject of the war. Whenever Fionna had previously asked years back, he would say that it was too horrible to recall and stop the conversation dead right then and there. He would get all quiet and stoney faced, making the atmosphere cold and uncomfortable. Fionna would squeak out an apology and steer their subject to something else that he liked to talk about instead. That would usually clear the air of any awkwardness but it wouldn't wipe away the fact that he simply didn't want to talk about it. Or that it bothered him enough to become genuinely angry with her. Marshall frightened Fionna sometimes when he would get like that so she tried her best to avoid stupid questions.

Cake, however, never experienced the feeling of strange silence with the Vampire King after asking such things. So, ignoring Gumball's immediate decline and Fionna's protests, Cake dragged the two of them down with her to the lair of the nightwalker himself. It was still early morning so Marshall was bound to be sleeping. But Cake didn't care. She wanted answers so her sister could get a good night's rest. Even though Fionna tried to point out that hearing more of the stories of human extinction might further her dreams, Cake waved her off and marched up to the door of Marshall Lee's home. She rapped her paw on the wood and waited, tapping her foot on the floor, arms crossed. Gumball and Fionna were standing behind her, trying to act like they didn't want to be there at all, which they didn't. The door opened a crack and the baggy eyed face of Marshall Lee poked through, glaring at whoever dared to wake him from his slumber. Then he noticed the cat standing defiantly on his threshold, looking up at him expectantly. Scowling, he threw open the door and transformed his head into a wolf's snout, making poor Cake cry out in surprise and fright, taking refuge behind Fionna and Gumball. Laughing evilly, he flashed his fangs at the feline, winking deviously. It was then he noticed the two others waiting behind the door.

He pulled open the door a little wider to fully reveal his body. Marshall Lee hadn't changed a bit. The only difference about him was his age. His demon genes were able to age him up by two years, making him biologically eighteen, for that part of him made him age slower than a human and actually made him age instead of a traditional vampire. But he still had the same hair, same blood-red, demon eyes, and same body stature: sometimes slumped but lean, light grey-green skin, and a cold touch. He had hastily thrown on a red and black plaid shirt and torn jeans to answer the door, showing that he had been sleeping. Marshall distractedly scratched his messy, raven covered head and mumbled a hello.

A little more confident with herself, Cake came out of her hiding spot behind Fionna's curvy legs and faced Marshall.

"We need to talk," Cake said.

"We?" Fionna and Gumball repeated incredulously.

"Whatever it is, I didn't do it," Marshall said lazily. "I was sleeping until," his voice deepened into a raspy warning, "you awoke me from my slumber."

Cake's tail frizzed a little and she gulped but stood her ground. "It's a matter of sleep or wake."

"What the stuff are you talking about?" Marshall said, raising an eyebrow. "And that didn't even make any sense. Usually, the phrase is: 'a matter of life or death.'"

"Fionna's been having these repetitive nightmares about the Great Mushroom War ever since Gumball mentioned the extinction of humans a few days ago," Cake said, fearfully watching Marshall's face get stonier and stonier like it had when Fionna asked about the war. "And we need to find out what happened just to see if it would stop Fionna's dreams. She's been deprived of sleep, Marshall Lee."

His red eyes skidded over to the human, who was trying to vanish from the scene completely, not meeting his eyes. This wasn't her fault, Marshall knew that. It was only a matter of time that she would start really wondering about what happened to her species, making it hard for her mind to focus on other things. Back then, she would shrug it off after getting soul search-y for a while but now... Nightmares about this kind of thing were expected. She was old enough to know, he felt. Before, when she had asked him a number of times, she had only been about fourteen. She was a seventeen year old girl now and she deserved to know the truth. He owed it to her.

"Fine," he said slowly, stepping aside to let them in. "But I'm only doing this because I think she needs to know."

Fionna and Cake walked over the threshold and into the house of the Vampire King. Gumball awkwardly stayed behind, wondering whether or not he was allowed to hear the story that Marshall Lee had been keeping for years. With a sigh, the vampire nodded at Gumball, allowing entry. Smiling in thanks, the Candy King walked inside, avoiding the rock hard couch that Fionna and Cake had taken to sitting on. Marshall shut the door behind him so his zombie poodle, Schwabl, wouldn't get out again. He floated over to them, who were all waiting patiently for him to begin his story.

A slight hesitation was noticed in Marshall Lee's movement as he crossed his legs in the air, hovering over the floor a few inches. He cleared his throat, trying to gain the confidence to remember everything that had happened to him.

"Just keep in mind," he said, "that I was young during the war. It's hard to remember everything about it. It was scary and confusing and downright traumatizing. Any time that you want me to stop telling the story," he said, looking at Fionna, "I'll stop. I don't want you to have anymore nightmares." The compassion for his friend was obvious in his tone of voice and Fionna was grateful for that. She nodded at him, to show that she understood. Marshall took in a deep breath and began.

"It started over one thousand years ago when humans began to grow suspicious of their neighbors," Marshall explained. "Conspiracy theories flew around like a disease, bombs were being created like they were a home cooked meal, and war was slowly approaching. What we now know as Aaa wasn't the paradise we all grew up in. This is my story..."

And chapter one is done. So do you like it? I hope so! I wanted to save Marshall's story for the next chapter because I felt it would be more interesting as an entire chapter (and then some at the end) than just a short summary. So I'll be introducing what I think happened during the Great Mushroom War.

By the way, I'm not only taking song submissions, but headcannons too. So if you have an Adventure Time headcannon you wanna submit, send it to me in a PM or write it out in a review and I'll give you full credit.

And reviews are appreciated.

See you next time!