There were plenty of things that Tobirama had been expecting Izuna to ask of him: to bring him back to the Uchiha compound, to never speak to him again, to spill all of the Senju's secrets. But he asked for none of those, though perhaps the elders would disagree as what he asked for was similar to the last.
"Teach me how to heal," Izuna spoke with conviction.
And who was Tobirama to say no? He invented the jutsu to help people, to honor Itama's memory, to prevent other people from losing their dear ones. It was never intended to be a Senju secret, at least not if they actually wanted the war to end. So he gave the man a sharp nod, promising to start lessons the next day as they were both too tired that night.
Besides, Tobirama had a lot to think about.
Izuna had surprisingly kept his word throughout Tobirama's explanation, despite the ugly twisting of his chakra at some points, and he was grateful for that. But he was still left with the dilemma of where to go from here. Izuna had made it clear that he was expecting the full story after they defeated Zetsu, and he knew all too well how stubborn the Uchiha could be. He would hold Tobirama to it.
Peace would be at stake either way he went about it, if he were to lie and come up with a convincing story (how could he possible come up with a story where he knew what he did about the sharingan without sounding like a bloodline thief) there was always the chance that Izuna would see through his deception. If he told the truth, well how would he react if Izuna suddenly claimed he was from the future and that his entire clan had been slaughtered by the village he'd never believed in and his brother had gone insane and was trying to take over the world?
Izuna would probably torch him on principle.
Hell, Tobirama would drown someone if they claimed such things about Hashirama. He paused and dwelled on that thought a bit more. Maybe he could see it actually. If someone told his brother that he could solve all the world's problems and everyone would be happy and peaceful by decimating the Diamyo's court, he'd probably do it gleefully.
Tobirama resolved to keep any such ideas away from his brother, and Touka who'd only encourage the mayhem.
He sighed, allowing the peaceful sound of the forest wash over him, he'd have to tell him. At least some of it anyway. But not now, not when their truce was as fragile as it was. After Zetsu was defeated but before they returned home, he vowed. That would at least give him time to figure out just how much he should reveal.
Somehow he hadn't pictured teaching Izuna would be any worse than his previous students, he was an adult for one, he already knew how to control his chakra for another. However, Tobirama hadn't accounted for the Uchiha's signature drama.
"Why fish? They're nothing like people, trust me I've gutted enough of both-" Izuna whined.
While Tobirama studiously ignored him, concentrating on the fish in front of them.
"I'm not letting you near another human being until you can keep this fish alive outside of water," he ground out, satisfied hearing the slight clack of teeth as Izuna finally shut up. "Now if you're done complaining we can get started."
"Of course, Tobirama-sensei."
Tobirama jolted at the unexpected honorific, despite how mocking it was. Izuna burst out laughing, and he knew that his horror must've shown on his face. Turning away from the fish, he jabbed the Uchiha in the chest with his finger.
"Do you wish to learn or not?"
"Yes, yes sorry," Izuna said between chuckles.
This was going to be a long lesson.
"You've seen me use the technique with your sharingan before, correct?"
"Yes, but without out any context to what you're doing it doesn't help me."
"Hmm, place you hands on mine and track my chakra with your own, see what I'm doing and try and mimic it."
Several hours past, far more time than either of them had truly wanted to devote to this endeavor today but they'd made progress. Not only had Izuna kept the fish alive but had healed the superficial cuts and scrapes it had along it's sides and the tears in its fins. Tobirama was impressed, it seemed the Uchiha had special talent for the techniques.
He'd told him so and hadn't been prepared for the swell of pride in the other man's chakra, how happy he'd been, nor had he been prepared for how it made Tobirama smile softly. He'd always been proud of his students accomplishments but maybe it was because he'd snuffed this life out before Izuna had the chance to discover these talents.
Forcibly pushing those thought away he reached for the fish to put it with the others for their dinner. Izuna snatched it away, still pumping it with chakra to keep it alive, his chakra growing prickly and defensive.
"Izuna."
"You can't have me keep them alive the entire afternoon only to expect me to be able to eat them tonight."
"It's a fish."
"No."
Izuna turned, cradling the fish and gently released it back into the nearby pond. So much for being a battle hardened shinobi.
The next day after travel, Tobirama dropped a field mouse into the Uchiha's lap, biting back the small twinge of satisfaction at the slight surprise that colored the other shinobi's chakra.
"Uh, thanks but I'm not that hungry," Izuna warily responded, cupped hands holding the frightened animal away from him.
"You really do need to stop thinking with your stomach," he grumbled, studiously ignoring the slight amusement that colored his voice, and the way Izuna's chakra swelled at the sound of it. "Congratulations you've graduated to mammals, hopefully you won't get needlessly attached to this one."
"It's a mouse."
"You're observational skills are astounding."
"Funny, I can understand the fish to teach me how to modulate my chakra. But what can a mouse teach me that the fish couldn't? Actually, when can we start learning about how to put people back together?"
Kami give him strength.
"The anatomy of a mouse is very similar to that of a human, learning to heal a mouse and eventually higher mammals will help you when you're ready to start on humans. After all, mistakes are common and expected while learning, and I'd much rather you make them on the mouse than someone you care about."
Izuna's chakra was prickly, but less out of anger but more embarrassment and irritation that likely related to the embarrassment.
"Ok," he sighed, "what do you want me to do?"
"It's got a broken leg. Bone is much harder to knit back together than skin and muscle, I want you to figure out how to do it on your own."
"What? I thought you were teaching me?"
"A fundamental part of healing is teaching yourself, you'll find that every person is different and techniques that work on one person won't work or would actually be detrimental to another. I'm here to guide you if need be, but I want you to at least try."
He could hear Izuna shift uncomfortably, as his chakra swirled with anxiety. Tobirama frowned, that was different. Why would this make the normally sharp-minded and headstrong Uchiha uncomfortable? He knew Izuna created his own jutsu, always countering Tobirama's own by their next battle, why was this any different.
"Izuna?"
The other man's chakra sharpened, causing Tobirama's own to withdraw and surprise, Izuna seemed to steel himself against whatever was going on in his head. With a sharp nod, he settled against a tree, using one hand to secure the mouse while his other slowly and carefully manipulated healing chakra over the broken leg.
After a few moments, Tobirama settled next to him, not speaking or interrupting in any way. Just there in case he was needed. And slowly, almost uncertainly, Izuna's chakra softened and melded almost with his own.
He didn't know how long they sat there, Tobirama eventually settling into a near meditative state. Letting his chakra stretch out, allowing his senses to drift to his outer range, he didn't often stretch his range out to it's limits. As it could be draining and exhausting, and dangerous as it ended up muting anything closer.
He frowned, noting two monster chakras clashing in the heart of fire country. He honed in on his brother's chakra, flinching at the raw hurt and grief. In contrast, Madara's chakra was twisted with hatred and rage. It was distressingly similar to his future-self's chakra signature. He tried to get a sense for their clanmates but their chakra signatures were drowned out by the clan heads'. It was distressing to say the least.
"Finally!"
Izuna's shout startled him, and he was on his feet with a kunai in hand searching for threats before he fully registered what was said.
His chest heaved, chakra lashing out looking for threats, looking for blank space, looking for Zetsu. For a brief moment he was back in the future, dust coating the back of his throat, the screams of shinobi crying for help as they were mercilessly cut down. His shadow clones tirelessly flicking between them, desperately trying to save those he could, his own hands tacky with drying blood. Madara's unhinged laughter rang across the field, setting his teeth on edge.
A strange chakra was gently poking at him, he twitched, lashing his chakra out in reprimand. What was that shinobi doing distracting him right now? The chakra came back more insistent, shoving at him now. It was warm almost like a smoldering ember, which was strange flame feeling chakra was typically something he associated with the Uchiha. Though, the chakra was rather familiar.
A breath, soft forest scents filled his nose, the screams dimmed and were replaced by crickets and leaves rustling. That warm chakra remained, Izuna's his mind belatedly supplied, the Uchiha's chakra was absolutely buzzing with anxiety as he seemed to flit around Tobirama. Pacing back and forth, he kept starting to reach out to Tobirama before thinking better of it and continued his pacing.
"Izuna," he croaked, which that was weird why was his throat so dry.
"Tobi!" Izuna yelped, almost throwing himself down next to him.
Tobirama arched a brow at the use of his nickname, but didn't comment as the other man flailed next him. A canteen was unceremoniously thrust into his hands, with the harsh order to drink before Izuna disappeared to the other side of camp. He'd barely taken a few sips before he was back with food.
"Izuna, I appreciate the effort, but this is unnecessary. We really should continue your lesson."
Apparently that was the wrong thing to say as Izuna's chakra froze, darkened, before exploding with rage.
"Unnecessary? This is unnecessary? You completely checked out, Tobirama! You weren't breathing!"
Oh, that might explain the tightness in his chest. He supposed he didn't need to breathe before so his body had forgotten that he did now during the flashback.
"Tobirama!" Izuna barked, breath on his face. Tobirama flinched back, away from the fuming Uchiha.
"My apologies for frightening you, Izuna, however it was merely a flashback. Nothing to concern yourself with."
"I've seen flashbacks, Tobirama, I've never seen someone stop breathing during one."
"I'm fine, can we please move on."
Izuna stared at him for several long moments, chakra a swirling storm of irritation and concern. But he thankfully seemed to allow them to move on, swiftly collecting a small bag that contained his mouse.
Grateful for the distraction, Tobirama took the bag and gently dropped the mouse onto his palm. He could feeling its rapid heartbeat fluttering against his fingers, twitching nose trying to find an escape. Absently rubbing his thumb over its head, he focused his chakra running it over the small creature and was satisfied with Izuna's work. He passed the mouse back, ignoring how his skin prickled under Izuna's glare, he didn't need eyes to feel that.
"Good work, you figured it out quicker than most," he praised, hoping for that little surge of pride in Izuna's chakra like last time.
Instead Izuna's chakra almost seemed wooden when released the mouse into the brush. Tobirama sighed, turning his attention away to start a fire, while also trying to forget the echoing screams in his ears.
As the days passed and Izuna grew more proficient with healing small mammals, Tobirama was grateful there was only one incident of accidental pet acquisition (he never brought Izuna another rabbit). The thick tension that had settled over them after his brief flashback and slowly settled. He wasn't stupid enough to think that Izuna had forgotten but he seemed to be willing to leave things be for now.
They were both shinobi, post battle stress and flashbacks are common if not expected in their line of work.
There was definitely a chill in the air now as they grew closer to the northern part of the Land of Iron border. He set to making a fire before Izuna started complaining about the cold again. They'd have to tread more carefully now, not only were they approaching Zetsu's hideout but also the Hatake's summer grounds. He really wasn't in the mood to deal with his cousins right now.
Fire started, Izuna had finished setting up their bed rolls, so Tobirama supposed it was time to set up his training. Pulling a kunai, lazily spinning it as Izuna watched him warily, chakra rippling curiously.
"We're getting close to Zetsu's hideout," he started, noting how Izuna's chakra froze in anticipation, "So it's time we advanced your training."
As he finished speaking, he slashed the kunai across his arm, carefully avoiding any major blood vessels. This wasn't the time to train Izuna in triage, he hoped there would be time later. That he'd be able to fill out this bastardized training program, there was so much he had skipped over to get them to this point.
Izuna yelped, chakra flaring in panic, and he was suddenly crowding his space. Tobirama was pleased to sense healing chakra flowing over the injury, cautiously accessing the damage.
"What the fuck, Senju!"
Tobirama was starting to get the idea that that was Izuna's favorite phrase.
"I told you, it's time-"
"Yeah I know," Izuna interrupted, "But you can't just do that without any warning, isn't there better ways to train this? Like on me?"
"Healing yourself is much more difficult than healing others, due to the pain and the fact that feeling your own body knit itself back together can be disturbing and can lead to mistakes. Don't attempt it without supervision."
"Yeah, yeah, you still shouldn't just slice open your arm, idiot."
A twitching nose pressed to his side, causing him to flinch, to Izuna's complete amusement. He'd forgotten the damn rabbit.
"See even Mr. Floppy agrees with me," Izuna said, chakra sparking with smugness as Tobirama's arm slowly healed.
