Due to the temporary paralysis that had been caused by Haku on top of the injuries he'd received from the Copy Ninja Kakashi, there had been little Zabuza could do other than sit and think as he recovered. One subject his thoughts constantly drifted to was his young cousin from Konoha. From there, his thoughts would head towards the rest of his family who were all gone now. Looking back on the fight, he had little doubt that he and the blond kid from Konoha were related. The boy yelled the way his mother had when his father had come home drunk and charged into danger with little regard for his safety like his uncles and younger cousins had been wont to do. The kid moved like them too.
Seeing the blond Konoha Genin had brought up many painful memories. The boy was brash and loud just like his uncle Ryu. Uncle Kenji had been more reserved, and his mother had been somewhere in between. The boy was also prone to making pointless speeches about becoming the Kage of his village, like his little cousin Midoriko who had followed him about everywhere when she was small used to do. All of them, his mother, his twin uncles, Midoriko, Akira, Hikaru, and little Momoko II had all been dead by his nineteenth birthday. It had been when he was nineteen and all alone in the world that he had found Haku.
His mother Karin had been the eldest of seven children who had been born to a family of Uzumaki in the now defunct Uzushiogakure. She had met his father during the Chunin Exams which his father who was roughly the same age as his mother had been proctoring at the time, and they had kept up correspondence. When they decided that they were old enough, they got married and settled in his father's home village much to the chagrin of his mother's parents. His mother had pretty much lost contact with her relatives until two of her younger brothers - the twins Ryu and Kenji - had shown up on her doorstep carrying their sister Momoko who had been exceedingly ill.
When his mother's siblings who'd still technically been children at the time had decided to join the exodus from Uzushiogakure during the invasion that had led to its fall, there had been a rather vicious argument. Ryu and Kenji had wanted to join his mother in Kiri, and Sato and Ao had wanted to join Kushina in Konoha. In the end, the Uzumaki stubbornness had won out and they had split up, with Momoko following Uncle Ryu and Uncle Kenji to the land of Water.
Aunt Momoko for whom one of his cousins had been named had ended up falling ill during the boat ride to the land of Water and died shortly after arriving in Kirigakure. A few years later, his mother had died giving birth to his stillborn sister after a rather difficult pregnancy when he was six. After claiming one too many times that there was a seal that prevented them from sharing the Sealing Arts with the village, his uncles and his cousins had been sent on suicide missions one by one until none of them were left. There had been no point in asking him who they'd refused to allow into the Academy because his family's unwillingness to share, because he hadn't really known anything he could share with the village. Eventually, he had killed an entire graduating class of a hundred students which had secured him his nickname and a spot in the Shinobi ranks alongside his cousins who had still been alive at the time. It had been the slow killing of his kin on the suicide missions that they had never once refused despite the fact that they knew they were being sent to die that had been a major contributing factor in his decision to kill the Mizukage and take control of the village that had slaughtered his family.
The entire family had known that his Aunt Kushina who was apparently the mother of the one cousin he had left had been special practically since the day she was born. While their branch of the clan was usually above average, Kushina herself managed to stand out on her own before she'd even been trained in the Shinobi Arts. It had been because of this and some other quality that Kushina had been selected to be the next Jinchuriki of the Nine-tailed fox. She had apparently done her job until about twelve years ago when something had apparently gone very very wrong. If what had gone wrong was what he thought it was - but it may not have been, considering the fact he spent more time focusing on swords than seals much to the disappointment of his uncles - he was pretty certain that he knew his cousin Naruto's birthday.
A twinge in Zabuza's shoulder brought him back to reality, pulling him out of thoughts of family that he'd spent years determinedly not thinking about until he'd encountered his young cousin. Now that he could move his arms properly as well as think about his family and his newfound cousin, he found himself occasionally rubbing the seal that was on his back at the juncture between his neck and shoulder. The permanent and so far irremovable seal was unique to the Uzumaki clan, and its creation was passed from parent to child. His own mother - apparently sensing her impending death - had left him the instructions in a scroll that could only be opened by him or one of his female descendants. He had not yet had cause to use it though, and he had no doubt that as Kushina's son, Naruto, had a seal just like his own. That seal had been one of the reasons he'd been reluctant to go all out against the boy after he began to get over the shock that he had a surviving relative.
On the day an Uzumaki child was born, either the mother or the father - depending on which was the Uzumaki in a mixed marriage, and whether or not the mother was up to putting the seal on the child at that time in an in-clan marriage - would place a certain seal on the infant. While one who was marked with that seal could argue and fight as much as they wanted with others who had the seal, a person who had that seal could not deliberately land a killing blow on another who had a matching seal. Had he not learned that Naruto was his cousin, things could have been disastrous. He could have been killed by the Copy Ninja Kakashi in the moment he was held back from killing the boy.
The question was, would he order Haku to kill the boy when the time came? Usually he would have done his mission and given the order with absolutely no hesitation, but...Naruto was family, and as his mother and uncles had repeatedly told him, family came first.
It would seem that he would have to cross that bridge when he came to it rather than make the decision now, considering how much he was wavering over it as he discovered a sentimentality he'd thought he'd lost ages ago along with the last of his cousins. For now though, he would focus on getting better.
Edited 2-27-17.