A/N: New story, Naruto cross over Adventure Time set during the period where Marceline was still a child, Simon wasn't completely nuts and there were still tons of human buildings around. For exact episode timeline I would say about a year before the events of the episode Simon and Marcy.

I don't own Naruto or Adventure Time they belong to Masashi Kishimoto and Pendleton Ward respectively.

Location: Konoha

Another explosion. Everywhere one looks the great village of Konoha has become a dancing red flower and the screams of civilians perpetuate the night sky as the choir to a symphony of death. Naruto Uzumaki, a spiky blond haired man who had electric blue eyes and three whisker marks on each cheek, the Hokage killed another invader. The invader dropped to the ground dead, a kunai in his throat and Iwa headband gleaming proudly. The stone village had attacked as peace was forgotten after Kaguya was defeated. Naruto prepared to activate the seal on his body, gathering chakra to his back the complex artwork of fuinjutsu hummed a pale blue. This seal was a time displacement seal designed to slow time around Naruto however fuinjutsu is a delicate art and even a master is prone to mistakes. One letter out of place, one line too short and the entire seal could blow up in the creators face. As Naruto activated his seal he felt something go wrong and panicked. Looking around in despair tears streamed down his face as his beloved village burned in front of him and he could do nothing as he felt his body disappear and a pull on his soul as it left the current area. Naruto said his last words before he disappeared from this time completely.

"Hinata, Sakura, Sasuke, everyone I'm sorry."

Location: Unknown.

Simon, a human man with pale blueish skin, a long nose and white hair plus a beard and moustache of the same colour. The man wore a suit and dress pants with a black bow tie and a large travellers backpack that held many supplies. Next to the man was a 7 year old girl who had pale skin, short and messy black hair and pointed ears. She was wearing a ripped red shirt with a blue overall on top. On her feet were red sneakers with grey and red striped socks on underneath, this was Marceline whose name was commonly shortened by Simon to Marcy, a nickname that would inevitably stick for the rest of her future immortal life. These two companions were scouring the ruins of a long dead city that held skyscrapers that towered over them like giants looking down on ants whilst mutated creatures skittered around in the shadows, the city absent of human life due to the mushroom war that eradicated their species.

A few blocks down at the crossing of four roads an intricate design spread on the floor and started glowing violet before shooting a pillar of violet light up that reached the top of the skyscrapers. Simon and Marcy stopped to stare at the light in shock before it died down and Simon stood in front of Marcy protectively in case anything emerged and was hostile. What neither were prepared for was a human man, around 18 years of age, to emerge once the light died down. He had spiky blond hair, three whisker marks on each cheek and a lean muscular build like that of a runners. He stumbled for a bit before his electric blue eyes rolled into the back of his head and he fell down unconscious. Marcy cried out in alarm and ran towards the man, Simon in pursuit behind her. Upon arriving at his body they found him wearing a black haori that had no sleeves and red flames along the bottom. Underneath which was a tattered orange and black jumpsuit that was completely ruined. On his feet were some weird sandals that were also destroyed beyond repair.

"We have to help 'im Simon, we have to," Marcy pleaded looking up at her blue skinned companion.

Simon just looked at the man thoughtfully gauging whether or not it would be possible to help another person, it was hard enough finding food and water for the two of them. But when he saw Marcy's face he relented and he had already decided, at least on a subconscious level, to help this man. So Simon simply responded with, "Alright."

Marcy smiled at Simon as he picked the man up and carried him into an abandoned building, missing the strange creature that watched them from the shadows.

3 – 4 Hours Later

Naruto groggily opened his eyes, his whole body sore from god knows what. Once he had enough brain function to think he immediately started to take notes on his body.

"Everything seems to be ok, oi Kurama you still in there?" Naruto thought and immediately got a growl in response to said stupid question from said Biju.

"Of course I am still here you stupid moronic human, if I wasn't you would be dead currently!" Kurama shouted back at his host.

Naruto winced in pain from the shout but said nothing more as he heard commotion in the distance. What sounded like a young girl exclaiming excitedly about him being awake. Naruto then saw a blue skinned man with a rather long nose look down at him from above.

"How you doing there kid?" The man asked.

Naruto could only cough in response causing a small hand to give him a glass of water. Naruto drank quickly and nodded his head in thanks to the disembodied arm. "I'll ask again, how you doing there kid?"

"Better thanks," Naruto rasped out, his throat still sore and voice scratchy.

"Good to hear now I just have one question to ask of you young man," Simon asked.

"Hmm?" Naruto replied.

"How is a human still alive?" The ice wizard dropped the proverbial bomb shell.

Naruto looked stumped with that question. It confused him, what had gone wrong with that seal that all humans were supposably dead. Deciding to get some answers first Naruto played his best card, the "play dumb" card.

"What do you mean, last I checked I lived in a village of humans and there were billions on this planet," Naruto said causing the man to frown and a young voice to speak up.

"But that can't be right the end of the mushroom war 2 years ago wiped out all the humans on the planet so how can you live in a village of them?" Marceline asked with her head tilted to the side in confusion.

Naruto looked shocked for a few seconds before closing his eyes as he tried to figure this predicament he had landed in out. "Hey Kurama you have any idea what could've happened?"

"When you used that time displacement seal something obviously went wrong, and what happens when a space time seal blows up in ones face?" The nine tailed fox asked its partner letting him finish the sentence.

"One is shot through space and time and could end up a few days after using the seal to a year, but after a year the human body can't take the strain of time travel and collapses in on itself," Naruto muttered under his breath, "Hey old man what year is it?"

"The current year is 2AMB (After Mushroom Bomb) or 2025," Marceline supplied.

Naruto held his head in shock as his eyes were the size of saucers, "O-o-over 1500 years into the future, how did my body survive the travel?" Naruto muttered to himself as he tried to come to terms with the fact that several hundred eras had passed since the era of shinobi.

"I can give you that answer," Kurama said.

"Kurama what did you do?" Naruto asked a little more harshly then he intended.

"I reinforced your body with my chakra throughout the trip allowing your atoms to stay together as your body once you exited the time vortex," Kurama answered.

"Is it possible to go back?" The blond Jinchuriki asked his tenant.

Naruto got a mental shake of the head as he got the answer he dreaded, "That was a one way trip unfortunately, if you tried to go back kit your body would be ripped apart and my chakra wouldn't be able to keep you together."

Naruto just lay there as he digested that. He was stuck in the future, all of his friends' dead for years, his wife Hinata died without him and his kids never had their father during their teen years. Naruto never got to see his children grow up and never got to experience becoming a grandparent. He had missed so much and he would never be able to go back to fix his mistake. All Naruto figured he could do now is make the best of a bad situation and continue on living, keep their memories alive no matter how much it hurt. He would continue on, he would make one last sacrifice for them by continuing to live and honour their memory.

He looked at his two saviours, the blue man and young pale girl. He owed them now. Naruto was no stranger to the situation he could see before him. A world where to survive it was hard enough to get food for one, let alone two. Yet these two have risked themselves by taking care of him instead of just leaving him out there to die. Naruto decided then and there that he would help these two strangers if they needed it, he figured it was the least he could do for the two who saved him.

"Thank you for helping me I realise that you could've left me out there but you chose to help me, I am in your debt," Naruto said to Simon and Marcy, his voice now back to normal.

"Kid you're in no-ones debt we only did what any good person would," Simon said.

Naruto just nodded his head and then looked down, looking back at Simon and Naruto scratched the back of his head and asked a question regarding his current situation, "Ah you guys have any clothes?"

Naruto was currently naked underneath the sheet he was under inside a broken down skyscraper. Simon produced the haori that was found on Naruto, however the colours were different. It was still black with no sleeves but the flames and kanji were ice blue now. Marcy then came into view with a bundle of clothes, which considering that would've had to scrounge around for them were quite ironic. A long sleeved orange shirt with a bone white fox skull depicted in the centre with crimson blood dripping from it. Slightly baggy black track suit pants that were ripped a little along with black sneakers. Then, much to the nostalgic shock of Naruto, he was given a red scarf the same red as the scarf that Hinata made for him as well as the two headbands he had on him. The first was his Konoha headband which had the same plating that Jiraiya had on his headband. The second headband was the headband of the aforementioned toad sage with the kanji for oil displaying proudly on it. Naruto tied these two headbands around his upper arms, one on each arm.

"Looking pretty good there kid, let me go grab Marcy and we…" Simon began before a scream was heard. Simon immediately sprinted out of the skyscraper toward where Marceline had gone in her haste with Naruto following behind him.

Marceline was being held by a truly strange creature in the opinion of the blond Hokage. It seemed to be made of green slime and had one single eye with a mouth that stretched from one end of its front to the other end. In its hand, tentacle, thing was Marceline.

"Gimme all your fucking stuff and the girl no get hurt," The thing said though it struggled as it seemed to find speaking hard, evidenced by its bad vocabulary and cliché threat.

Simon just put his hands up in surrender before moving to take of the pack he held. He knew just how difficult it can be to deal with these things as even they weren't completely aware of what they were doing. "Ok I'm taking this off to place on the ground for you."

Simon said this slowly so that the slime creature understood. Before he could place it on the ground though the blond they saved walked forwards before speaking when he was in front of the creature.

"I never caught your name old man," Naruto said as he crossed his arms.

"Simon, Simon Petrikov," Simon said upon realising that he indeed never gave his name.

"Well Simon I told you I was in your debt, I intend to help you guys out so just let me deal with this," Naruto said as his eyes hardened and a cloud of smoke enveloped him as the back of his right hand glowed blue with a seal, "Scum like this don't deserve to live anyway."

When the smoke cleared Naruto stood with a war hammer with a head that was rectangular and blunt on both ends. The head was made of white marble whilst the shaft was made of chakra conductive metal with leather straps wrapped around it. Upon the leather was the design of a winged serpent coiling up the shaft. The head was on the ground with Naruto holding the bottom of the shaft with his right hand, the whole thing coming up to his chest and the end of the shaft was a spike.

With a kick Naruto spun his hammer up and around to catch the middle of the shaft in his left hand before charging at the monster. The monster threw Marceline away but Simon quickly ran over and caught her before both watched Naruto swing his hammer at the creature. It impacted but went straight into its chest due to the structure of its body not being solid.

The creature laughed thinking itself invincible until it heard Naruto chuckle. The hammer head then glowed softly blue whilst it also began to softly hum. A large wind picked up along the shaft as the serpent lit up blue as well and then the head exploded in a gale of wind, dispersing the slime that made up the arrogant monster everywhere. Placing his hammer on his right shoulder Naruto turned to the shocked travellers, his new companions he thought with a small smile.

"Well Simon, Marcy the names Naruto mind if I stick with you guys for a while, I don't really know my way around this place," Naruto said and Simon just shook his head in amazement before standing up and walking off with Marcy on his shoulders.

As Naruto watched them leave Simon looked back at him, "Well if you're going to travel with us kid then you better pull your own weight," Simon said before looking back and continuing walking.

Naruto smiled, resealed his hammer, and jogged up to them and walking beside Simon. His look then turned thoughtful. He was in the future but he had new precious people that he would protect with his life, and he had no doubt that his life would be on the line if what he saw was correct. For when he dispersed that slime monster he saw a scrap of cloth inside it. A scrap of cloth Naruto knew shouldn't exist anymore as he destroyed all traces of those terrible garments that scarred the shinobi world. A scrap of black cloth with a red cloud on it.