There had been stories of children civilian and otherwise finding that they had an unexpected Kekkei Genkai and learning that they had an ancestor from one of the clans that had wandered through the region of their birth before the founding of the shinobi villages. Most of the stories were disbelieved, though there were a few odd Hyuuga who had never attended the Academy and had seemingly cropped up out of nowhere...
This is the story of one such child. Not one of the mystery Hyuuga, a kid with a random Kekkei Genkai that he supposedly shouldn't have had.
The story could arguably begin in the land of Wave when the Kekkei Genkai had seemingly randomly appeared, but it could also have been said to have started in two different places on the same day nearly eighty years before. One place was the main Uchiha Encampment, the other was an inn several miles away.
While the Uchiha all had houses somewhere, the clan was constantly in demand for missions and battles, which meant that they rarely if ever got to see said houses. Occasionally, they came home to discover that their houses had been looted down to the foundation while they were gone, and that just about everything - including things that had been nailed down - was missing. The Senju were usually to blame for this, and the favor was just as often returned as it was received.
As soon as a Uchiha was deemed old enough for travel, most of his or her year was spent living out of a bag in a tent, or just living out of a bag. Life in the camp wasn't all that bad though. There was a sizable band of people who made a living following the Uchiha around providing goods and services for them in exchange for the pay their high quality demanded. They were willing to take this risk, because the Uchiha were willing to protect their "entertainment", so long as said "entertainment" didn't follow them somewhere where they ended up being an unnecessary distraction. Madara's decision to allow the strip show to come within a mile of the camp had been the best one he'd ever made as far as a good number of the men were concerned.
Inside one of the tents clustered around the central water source that was a well this time, which everyone had agreed was a vast improvement over the slightly murky pond they'd last been clustered around, one Uchiha Hikaku was ahem, busy with one of the camp followers. Uchiha Hikaku was a young man of fairly average height with the long face and pointed chin that was pretty much standard in the clan. He had dark brown hair which he kept up in a short ponytail, and eyes that were ink black when they weren't Sharingan red. He was strong, and well regarded by his peers. Hikaku's current companion was a rather voluptuous blonde with brilliant blue eyes who claimed that her family name was Namikaze. Whether or not this was true was up for debate, as the camp followers tended to take up aliases on the road for various reasons. She hailed from parts unknown, and had been following the Uchiha around for only a little while. She wasn't as pure as fresh driven snow, nor was she one of those whores that even those who were too ugly to get a girl of their own were afraid to touch.
That suited Hikaku just fine since he wasn't looking for a wife at the moment.
While Hikaku was occupied with his companion, several young adolescents were experiencing the joys of a meal that didn't come out of a communal cooking pot half burned at an inn several miles away while their cousin and teacher was occupying himself with other things in a room upstairs. One of the first things a Uchiha learned when he or she joined the clan in their travels for missions was that they were pretty much on their own for food because their fathers, and in some cases mothers, weren't going to cook for them any longer. Buying grub from the camp followers was expensive, and couldn't be done too regularly on the cut they received from the Clan's pay. Hence their usual practice of pooling their resources and having the best cook in the group deal with the cooking. The current best cook of the current generation royally sucked however.
This part of the story isn't about the youngsters who were scarfing the food in front of them down as if they'd been starving for weeks, despite the fact that the adults in the clan made sure they were provided for in that area. Even if it meant that they went without. It's about their teacher Uchiha Izuna, co-head of the Uchiha clan and brother to Uchiha Madara whose spur of the moment decision to take a woman who'd found him "cute" up on her proposition would have long-reaching consequences.
While the children ate, Izuna kissed the sleeping woman who had shared his bed one last time before he got up to get dressed. He knew that he was going to get a talking to, or yelling at rather, from his brother over this. While the woman hadn't given her family name the evening before, it was as obvious as her long red hair. The Uzumaki were related to and allied with the Senju, therefore making it a strong possibility that the woman he'd met while herding the brats to some minor training mission was a spy, considering the fact that she hadn't tried to kill him the second he'd gotten close enough to kiss. The adrenaline high from the danger he'd known he had been in had been exquisite, and the yelling at he'd receive from his highly protective brother didn't make it any less worth it. What was done was done, and what was done was fun.
Izuna would later come to regret leaving the woman while she was asleep rather than waking her up to at least say goodbye. She stopped chasing him eventually - when she became too pregnant to run in fact - but the damage was done, and as far as he and Madara were concerned, if they ever heard the word "Dattebayo" again, it would be too soon. By that point, Izuna didn't care whether or not the child was actually his. He never wanted to see its mother or her brothers again, and if the kid was like any of them...
While a certain Uzumaki was giving birth to a rather beautiful daughter with hair so dark red it was almost black and inky black eyes in the land of Whirlpool, a certain blonde was giving birth to a brown haired son with inky black eyes in a place that would soon become part of the land of Fire. Neither child would meet the other during their lifetimes, and neither child would show any sign of developing the Sharingan. Unlike the Byakugan, the gene that allowed the Uchiha to unlock their Kekkei Genkai was recessive.
Izuna's daughter would grow up to be quite the beauty, and would gain one hell of a reputation on the battlefield where she brought glory to her family and the village of Uzushiogakure as a whole. Eventually, in due time, she settled down and married another Uzumaki. They ended up having a lovely daughter and several healthy sons all with the standard Uzumaki features and dark eyes. The daughter would never show any signs of the Sharingan, though one of the girl's brothers would shortly before he died in battle.
Hikaku's illegitimate son would move to Konoha as a child and grow up to be a reasonably handsome if rather average shinobi who would survive the First Shinobi War. He ended up settling down with a rather beautiful platinum blonde medic he'd met after becoming injured. They would have a blond haired, blue eyed dim and somewhat scatterbrained son who showed absolutely no signs of having the Sharingan.
Neither Izuna's granddaughter nor Hikaku's grandson would meet. Izuna's Granddaughter would marry another Uzumaki, and Hikaku's grandson would marry a rather pretty Chunin with sun blond hair and blue eyes and nice...assets, as Hikaku's preference for blonds had apparently been handed down the line for a time.
It was been Izuna's great-granddaughter and Hikaku's great-grandson who would meet. Neither Uzumaki Kushina nor her Academy classmate turned boyfriend turned husband Namikaze Minato, Yondaime Hokage of Konoha, would have any inkling that they were related to the rather sizable Uchiha clan that also made its home in Konoha as Minato's grandfather had considered the man who raised him to be his father and never said anything about the man who had sired him to his children, and Kushina's grandmother had only gotten a terse "He's dead" in reply to any questions she'd asked about her father. Neither Kushina nor Minato would show signs of having the Sharingan, though there would be some questions about exactly how Minato had been able to keep up with things when he was using the Hiraishin to take down fifty to a hundred opponents practically all at once.
On the day Kushina and Minato's son Naruto was born, a man claiming to be Uchiha Madara attacked. While he was removing the Kyuubi from Kushina, he found himself wondering about a certain possibility after hearing the woman say "Dattebane" like she always did since he'd heard a number of interesting things when the real Madara was in a grumbly mood and inclined to ramble. While there may have been something of a resemblance about the eyes, the Uzumaki woman didn't look anything like Madara and therefore consequently Madara's brother Izuna, and that annoying verbal tic was more than likely a common problem amongst the Uzumaki.
Twelve years later, on a bridge in the land of Wave, under a dome of ice mirrors, two boys suddenly found it much easier to track their exceedingly fast opponent. At one point, when Uchiha Sasuke had briefly looked his teammate in the eyes, he'd gotten the shock of his life when he'd found another pair of Sharingan looking back into his own.
He managed to get out a surprised "What..." before several senbon temporarily took him down for the count.