Not all Senju were as gifted sensors as the Uzumaki, but, nonetheless, they all felt it. A sudden hair-raising shift in the flow of Nature chakra, chakra they could not generally perceive, but whose detectable activity was, because of this, much more conspicuous. It felt as if someone had taken a needle to the net that covered the world and put a little hole through it. Nothing big, or world changing. But perhaps all the more disquieting for it.
It was something that demanded an investigation and, should it prove a problem, a subsequent solution before it became a threat. Given the hole's proximity, the investigation could not be delayed. If they didn't do something about it, undoubtedly someone else would decide to look into the matter and the compound's location would be compromised.
But, like most clans whose main source of income was mercenary work, the main body of the Senju shinobi forces was off on missions, leaving only a few high-caliber ninja in the compound. And so, after some deliberation, it was decided that the clan head and his second son would go, ensuring a team that was powerful, but whose loss would not be wholly debilitating ( if it came to it, the heir was safe and more than capable of taking the reins).
Tobirama felt tense as he ran towards the disturbance. To his right, his father looked grim, pale lips glued in an unforgiving line. He could sense the places where chakra gave way to something utterly foreign and now that he was closer he realized that there were two different sources. The trees around him provided cover, but as seconds ticked by and he started to really grasp the extent of his discomfort, he wished for a more exposed terrain, one that would have already allowed for visual contact and the end of his anxiety. The forest was unnaturally quiet, with only the rustle of leaves and his own heart beat to accompany him on the way. As he concentrated, he realized the holes didn't draw the sen chakra in, as he would have expected; however, the way they interacted reminded him of his last time swimming in an ocean, when Hashirama's marriage was being negotiated in Uzushio: of the giant jellyfish that kept tentatively prodding him, trying to anchor itself, tireless despite his skin's lack of give. It hadn't succeeded, as human skin was not made to accommodate tentacles hooking through it, and, similarly, the tendrils of natural energy that tried to breach the gap didn't seem to be progressing.
He froze the moment he saw something, signaling his father. They both stopped short. Tobirama could feel that a good deal of the space straight ahead was in fact occupied by otherness, but disturbingly there was no sign to mark this. It looked just like the rest of the forest. Although he was dead curious about what would have happened, he breathed a sigh of relief when he saw that the rift wasn't superimposed over the trees or the undergrowth, but rather it was floating. Though maybe he was misusing the term 'floating', since rifts in reality were unlikely to move around or feel the effect of the planet's gravity. Would it disrupt a physical chakra system, he wondered. Nature chakra flowed freely outside of living organisms, but if he lifted a flower so that its rudimentary network was partially found in this unknown, empty space, would its channels continue to function? Would it be destroyed, or wilt immediately? Deciding he couldn't take the risk of the hole corrupting its network and spreading further, despite his curiosity and itching palms, he chose not to become a prospective Horseman of the Apocalypse and buried the thoughts of potentially world-ending experiments.
Honestly, it could have been much worse: a disaster of apocalyptic proportions, coming in flavors like planetary chakra drainage, black hole or alien invasion. He almost chuckled nervously at the thought, only to swallow it as he looked down. Because lying underneath the rift and mostly hidden from view by a tree, was the second gap in the chakra web. And it seemed to be wearing boots.
Butsuma tilted his head and they circled around the tree, avoiding the suspiciously inconspicuous patch of air. Only to feel his worldview shift when the body the boots had belonged to came fully into view. There was, for lack of a better world, an alien lying on the ground. There was nothing else it could be: the lack of chakra betrayed its foreign origins. Even corpses had some chakra, if only that of the organisms responsible for decomposing the body.
It almost looked human, if you only caught a glimpse from the corner of your eye, but there was no way to make the same mistake from this perspective. It was huge, easily a head taller than any man Butsuma had ever seen, with a big head and features that were all the more strange for their similarities to his own. Its skin and hair had textures that defied common sense, and its members appeared to be covered in a thinner layer of hair as well. A moment of reinforcing his hearing with chakra was enough for him to declare:
'It doesn't have a heartbeat. Doesn't seem to be breathing, either. Think you can recover any relevant information from the body?'
Tobirama nodded, kneeled, and placed a hand on its torso. And this is where several things happened in quick succession, not all of them ever to be known by any of those present. Chakra, by nature, was made to spread. So when Tobirama's hand came into contact with something lacking any chakra at all, human chakra being much more willful than nature one, it tried force its way in. But this was not a container that could manage energy in this form, so it reacted , trying to translate it into a comprehensible stimulus, which resulted in enough electricity to kick-start a heart and made Lichtenberg figures bloom across the alien's skin. But the body learned to deal with the influx soon enough and prevented further invasive action; what it didn't absorb was thrown back at Tobirama.
The only scenario in which one might get blasted with chakra that, coming from an external source, would match the exact frequency of one's own was meeting a soulmate. There was nothing that could perfectly reflect pure chakra, since everything had some of its own. So it was really no wonder that Tobirama's body reacted accordingly, with new marks stretching across his skin and glowing faintly and a heavy load of adrenaline being suddenly dumped into his system. Tobirama's breathing seemed far too shallow in contrast to his frantic heartbeat. He could feel immediate adrenaline high the bond had triggered, along with a haze that he guessed was brought on by the plethora of hormones his body must have been producing. It was like a frozen finger that was being warmed too fast. He wanted to crawl out of his skin, away from this overload of sensation. Somewhere at the back of his head, a voice was distantly taking notes on the effects of this chemically induced attachment, but he mostly felt feral, like he might claw or bite at the slightest provocation. Objectivity went right out the window. A heaving gasp tore him from his trail of thought, panic drowning him at the thought of how close to losing his mate he had been. He tried to push some healing chakra through, to help the resuscitation, but it only lit up his mate's marks, refusing to sink through skin and do its job.
Mates were rare. In the entire Fire Country, there couldn't be more than a dozen; in the whole world, there were perhaps a hundred. Rare enough that people didn't worry about touching their targets and enemies. Rare enough that the possibility of it hadn't even crossed Butsuma's mind as a possible danger when his son was about to touch an alien. Thoughts of foreign pathogens and automated self-defense mechanisms seemed much more pressing.
But he'd watched the being twitch, as marks spread across the surfaces of their skin, watched Tobirama's pupils swallow the red of his irises. And all he felt was a viscerally imposed distance. A voice in his hind brain that told him the ones in front of him were now something... other. The alien drew a mouthful of air noisily, and Tobirama's chakra went green, highlighting the marks on the stranger's skin. It didn't appear to have any other effect and his son let out a dry sob, moving to lift his mate's torso and make breathing easier. He seemed to have a disproportionate amount of trouble with the task, hinting that the alien was much heavier than expected. It didn't take long for its breath to even out and its body to relax, hinting at deep sleep or unconsciousness rather than the stillness of a corpse.
The bond was already settling in, making its effects apparent. Tobirama could feel his system getting back on track, only, instead of the nausea and weakness that usually followed an adrenaline rush, he felt better than before. Better than ever, really. The trace amount of his chakra in the stranger's marks made his presence a great, if previously unknown comfort; resonating at the same frequency as his own, it amplified his stores, leaving him well-rested and energetic. His mind was clear as a bell and he felt focused and attentive. He now understood the reason artists seemed so keen to express the sweetness of love. Just being in his other half's presence left him feeling serene, warm and affectionate. He could tell that the feeling was fabricated, but it seemed unimportant in the face of this empowering rush. He knew nothing of his mate, but already his tastes had changed, making those foreign features ideal, rather than strange, to his eyes. He had no doubt that, whatever his personality or actions, the bond would more than make up for. War and suffering didn't matter anymore, because all of Tobirama's world was right there in front of him.
Watching its chest lift with every inhale was as unnerving as it was reassuring. Tobirama studied the alien's head, drinking in its features. He laid one if his hands tentatively against the other's hair, which felt wholy different from anything he'd encountered. The individual hairs remaned easily visible at all times, rather than blending into a uniform mass. And the hues! The hairs each had a different one and it was only the weakness of the eye that gave the impression of a homogeneous colour. If he looked closely, he could find shades he'd never imagined existed. And it was with that thought in mind that he took his decision.
'I'll seal the rift, so that it doesn't send anything away or corrupt the chakra.'
'And so that it'll never be able to return where it belongs', judged Butsuma.
He was unlikely to survive in an environment which suited such big, sturdy beings and was entirely devoid of chakra, Tobirama thought. And he wanted to live now, more than ever before, because life now meant warmth and fullfilment, instead of oppressive duty and ceaseless pain. If he couldn't leave, then his mate had to stay. There was no other reason for which he would have trapped them both in a world torn by endless war otherwise.
And it had to be a secure trap because, while he was sure the bond would also work its magic on his destined, he couldn't be certain of the background it would fit into. His mate might have a family already or belong to a society with other values; hell, his mate's home world was likely to have been better, if only because there they wouldn't have been the only one of their kind. Tobirama knew that he would never be able to give up the bond, so he proceeded to do what he did best. Ensure that the most likely outcome of his endeavors would be a favorable one. His mate wouldn't leave if there was nowhere to go.
So he gave his father a slow nod and stared him in the eye, knowing that there was no sensible reason for Butsuma to forbid his preferred course of action. After receiving a nod and a grunt of acknowledgement he got to work, creating what would have to be his masterpiece in time-space sealing. But the symbols came to him almost faster than his brush could write, reinforced by his motivation: he couldn't allow the risk of losing all this. So he worked around the portal and bent space to his will, seemingly erasing the rift from reality. By the time he was finished the sun was setting and the air had chilled. Tobirama turned to his father and told him:
'The hole, of course, gradually closed on its own. We kept it under supervision until it just seemed to wink out of existence'.
My mate can never know, so the story of what went down today cannot spread, he didn't say.
Butsuma considered his words, then mentioned:
'Someone needs to cover the supply lines.'
They both knew it wasn't going to be Tobirama who left the compound for weeks on deliveries anymore. His son agreed to the unspoken trade : word of the day's events wouldn't get out and Tobirama would train someone to match his prodigious speed in order to take over his most strategically significant duties.