Tobirama should have known the moment he realized Izuna wasn’t on the battlefield and sharpened his senses to feel him back in the Uchiha compound. He should have realized that only being on death’s door either injured or sick, would keep Izuna away. And that would mean he could be sleeping, could be watching. So when Tobirama felt the quiver and steel of terror in Izuna’s chakra, Tobirama felt stupid. Because his soulmate was watching him cut down his own clansmen. After the shocking realization, Tobirama had closed his eyes and pulsed his chakra out towards Hashirama, feigning injury in order to pull the battle to a close.
That was all fine, and he used a jutsu to induce sleep in order to see, and what he did confirmed what he felt. The vision was blurry, with tears, as the fuzzy image of Madara fills it. Tobirama had scared his soulmate—no, had terrified him. And he feels shame, because he feels like he’s wronged his soulmate on such a deep level.
When he wakes from his customary post-battle power nap, he’s greeted by Hashirama’s worried face.
“Father’s been asking how you’re doing.”
“And what did you tell him?” Because Hashirama wouldn’t find any injury that needed healing, would know that he feigned an injury. Father would be incensed, and Tobirama doesn’t look forward to his punishment. (After all, with Izuna off the field, Tobirama was doing a very good job on cutting down the Uchiha.)
“I told him that you’d be fine by tomorrow.”
Tobirama looks away. Father would accept that; Hashirama will want answers. And sure enough, Hashirama speaks again.
“How long have you known?”
For as much as Hashirama acts and talks like an idiot, Tobirama knows he’s not stupid. Hashirama simply gets distracted easily and never responded well to any disciplinary actions. The best thing you could do with Hashirama is point in a direction and hope something over there catches his attention. But it looks like Tobirama didn’t distract him enough, since clearly he’s figured it out.
“A while,” Tobirama admits, barely above a whisper, “and today—”
His words get stuck in his throat as he remembers the feeling of terror in Izuna’s chakra, of the blurry vision and how he clung to Madara.
“—today he was terrified.”
Tobirama watches as a look of understanding forms on Hashirama’s face.
It speaks volumes that Tobirama doesn’t respond to that and simply allows himself to be swept up into a comforting hug. Hashirama’s petting his hair and humming (both nervous ticks of his that Tobirama usually responds by telling him that he’s not a cat, Anija, go find one and stop bothering me), but today Tobirama lets it happen.
“You can’t tell Father.” Tobirama pleads, only on this side of panic by Hashirama’s soothing.
“Of course, of course”—Hashirama pulls back and grips Tobirama’s face firmly between his palms—“Don’t worry about Father, Tobirama. Anija will take care of everything.”