Disclaimer: I don't own Naruto or Fairy Tail.
Rechecking the complex seals a fortieth time, the man pursed his lips as he steeled his fluttering heart. Once upon a time, he would have just activated the fūin array and winged it; that segment of his life had passed rather quickly. Now, paranoia ruled his world as he peered cautiously at the massive array that spanned the entire floor of the basement he stood in, making sure not even a single stroke was overly thick or thin. Drawn in his own blood, the fūin was one of the most complicated ever designed; even the lost Uzumaki fūinjutsu couldn't hold a candle to what he had painstakingly formulated over the past year.
Hiding in dark, dank basements lit only by flickering candlelight would not have crossed his mind a year ago. As it were, the whole guerrilla shtick became necessity when Uchiha Madara managed to activate his Eye of the Moon Plan. Everyone but he and Kirābī succumbed to the Mugen Tsukuyomi that was cast. The rapping Kumo-nin only grinned at him disarmingly as he held off Madara for what scant time he could, to allow for his fellow jinchūriki to escape and counter the sinister plan. Even the use of Kyūbi's chakra was ineffectual; all it did was make the ninjas sick from chakra poisoning. With even the most crude of dispelling techniques useless in the face of Mugen Tsukuyomi, he figured a return to his familial roots might provide him the answer.
Hence he journeyed across the lands in secrecy, using all his hard-earned abilities to avoid detection. He was genuinely surprised the masked man had not been able to track him down, but that surprise quickly evaporated as he realised just how much time he would need to create a counter. Since then, a healthy dose of paranoia and the most painful of chakra suppression seals have kept him from being found. However, it was barely a meaningful existence, with the whole world succumbing to a mindless fate.
He found nothing. There was no seal, no technique that could release the Mugen Tsukuyomi. Instead of letting despair overwhelm his increasingly fragile heart, he gained inspiration from the various male figures of his life. The greatest practitioner of jikūkanjutsu, according to Jiraiya, was lost to the world when the Nidaime Hokage sacrificed himself to protect the lives of his team from the Kinkaku Butai. But the concepts were still explored after the great man's death, and works like Hiraishin no Jutsu were created and used to devastating effect. Kuchiyose no Jutsu and Kamui were also paragons of the fabled and exceedingly difficult art, but he was willing to try, even at the cost of his life. He was the last one standing, anyway. If he didn't do it, no one could.
With the idea to twist space-time to his whim and fancy, he settled down in a small village, where he hollowed out a place for his work underneath an abandoned straw cottage. Seals plastered the cottage above ground, preventing his enemy from discovering his location or worse, utilise his work for even more nefarious purposes. Half a year of head-scratching later, he had a design that he was confident in. Even Kurama expressed his admiration for the sheer complexity of the fūin, and was fully confident in his partner's array.
Time travel was merely an intriguing theoretical study for many fūinjutsu experts until he found the dire need for such a crazy fūin to work to specification. Sure, manipulation of space-time was almost commonplace, but to take a step backwards in time was deemed a pipe dream for even the most confident and skilled of fūinjutsu masters. No one even had the bravery to create one, in fear of completely annihilating all life in the world. It was a distinct possibility that he tried to push to the back of his mind. No need the added stress of actually killing everyone in the midst of attempting to rescue them. Kyūbi helpfully reminded him of time paradoxes too, but given that nobody had actually jumped back in time before, he reckoned he could deal with the consequences when the array actually brought him to where he wanted to go.
Hesitating for the better part of a month, he had finally summoned the courage that he once possessed with abundance. He rationalised his fears by gathering equipment for the journey. As a man who didn't belong to that particular time (or parallel dimension, which was another realistic possibility he tried very hard to ignore), he would need weapons, clothes, and food to sustain himself without having to interact with anyone. There was no telling what sort of changes would happen if he spoke to even one person. The butterfly effect was often derided as a slippery slope fallacy by the scant few philosophers they had, but he knew better than to tempt fate.
Glancing one last time at his massive seal array, he swallowed nervously. Clasping his hands in a hitsugi seal, his body was cloaked in a dense cloak of azure chakra. He would be lucky if he had a minute to activate his seal and avoid capture by Madara, which would finally seal the fate of the world. Even the multiple layers of seals he planted on the cottage would not be enough to mask the voluminous energy he was putting out. Without a sound, the chakra started to flow into the crimson array beneath his feet, the seal lighting up in a bright sapphire glow. The light engulfed his lanky form, and bit-by-bit, his body dissolved into brilliant particles that shimmered in the blinding glow of the fūin.
By the time Uchiha Madara arrived at the small cottage and eradicated the straw hut with all the impunity of a tantrum-throwing six-year-old child denied his toys, Uzumaki Naruto was nowhere to be found.
His eyelids flew open to an unfamiliar ceiling. He hadn't felt the soft comfort of a mattress or the gentle warmth of a blanket for months. Casting his sharp gaze around, he quietly analysed his surroundings. The cosy home was built into what seemed to be the hollow of a massive tree. The walls were covered in green bark that pulsed with abundant life. Shelves of tomes were scattered around the place, along with a simple table that stood to a side, holding a pretty porcelain tea set on its top. A particularly large window that stretched from floor to ceiling was beside the bed, ensconcing the room with the sun's warmth. The view, however beautiful, held no interest to him at the moment.
But even the radiance of the sun was not able to elicit a smile from the emotionally and physically drained shinobi, far too jaded to appreciate the glow of the sun despite his lengthy disassociation from it. Struggling into a sitting position, he winced as he opened some fresh stitches. Crimson bloomed on the swathes of bandages that wrapped around his torso, arms and legs. Chalking it up to the stress of the travel, he spied his clothes and belongings sitting on several wooden barrels behind the head of the bed, completely unscathed. There was a certain wave of relief that swept his body then, but it was immediately replaced by concern. Would the person who brought him there be instrumental in the world? Would his presence twist the fates into something unfathomable? Would he be able to rescue his loved ones?
Shutting his eyes, he stilled his body as he crossed his legs into a meditative pose. Diving into his mind, he stifled a gasp as he was met with a blank, white space. There was nothing; it was reminiscent of the part of his mind Namikaze Minato brought him to when he helped subdue Kurama. Slipping out of his meditation, he cringed at the pain that blossomed from moving his hands together. Clapping them in a hand seal, he stimulated his chakra coils, looking desperately. A modicum of chakra remained in his reserves, most of it spent on the seal. But there was no taint to be found, no foreign chakra to be discovered. With no regard for his health, he ripped the bandages around his abdomen off. Even as he moulded the pitiful amount of chakra he currently held, he should see a large spiral seal array materialise on his skin. There was none.
A single tear coalesced in the corner of his brilliant blue orbs as he pondered the ramifications of that revelation. He no longer held Kurama. For a moment, he wondered if the bijū missed him as much as he missed the fox. Laughing bitterly, he desperately hoped the reason for the disappearance of Kyūbi from his stomach was due to some time paradox. Gingerly lowering his bandaged feet to the carpet that covered the centre of the room, he wriggled his toes against the soft curls of the rug, feeling far more at home than he ever did back in Konoha, when things were still simple. Standing in spite of his severe injuries would usually garner much anger and exasperation from the medical staff in the hospital, but he always did it anyway. There was to be no exception here; he needed to know where he was.
Grasping the stiff support of the bed to steady himself, he inched his way towards the ornate door. Elegant curves were carved as part of the design of the wooden entrance, but Naruto had no interest in architecture, and couldn't tell which country that pattern would belong to. Every step was a mountain to climb; he never felt more grateful for Kurama's grudging assistance in the past until then. Stumbling on the edge of the carpet, he still managed to clutch the door handle in his haste. His knees hit the ground with a loud crunch, but the pain barely registered as the man pulled himself up with what he would call determination and what most would call sheer stupidity.
The door opened easily, and in his rush to see his current locale, he nearly stumbled down the steps that led to the house. The beauty of the landscape went unappreciated for the moment, as Naruto collapsed to his knees once more. A strangled sob made its way out of his throat, as he clutched his face in sorrow. The hot, unbidden tears leaked from between his calloused fingers as they hit his lap with soft plops, soaking the bloodied wraps with even more liquid.
Naruto knew most terrains by heart. He studied extensively, in order to be able to recognise his surroundings when he finally pulled off his time travel technique; in order to live off the land until he could bring Uchiha Obito down somehow. He knew the flora and fauna of the Elemental Countries by heart, and if his friends had been alive, they would be thoroughly amazed by the knowledge he gathered so meticulously.
He couldn't recognise any of it.
He had failed.