Friendship
He felt it first, a small fluctuation in the other's chakra. Then a spike, and then another. By the 5th spike, Tobirama was already out of the compound. He was 12 but no adult in his clan could stop him now, and couldn't catch him if they tried. Tobirama ran, through the trees, across the makeshift battlefield to where he saw Izuna lay in the dirt face up with an older shinobi, a Hagaromo (bastards), standing over him. He heard a cry from farther away, two cries actually. But without fully thinking and being full of adrenaline, he lunged at the bastard who had been raising a sword far above his head. He punched, and kicked, and by the end he had ended up using his most recently made jutsu Ketsueki jokyo - blood removal on them.
With the immediate threat officially gone, the adrenaline faded and he felt the pain in his abdomen and looked down to see the hilt of a blade sticking out, his own blood slowly pooling around it, making his obi warm and wet. He sank to his knees and coughed, the copper taste not new to him, just unpleasant.
Together two surges of immense power lifted around them as Izuna crawled over to him. His left leg was twisted at a weird angle, but no punctured skin… he would fight again after he healed.
"You dumb fuck, I had him!"
Tobirama coughed some more.
"He was-" he tried between labored breaths. "crushing your neck…..with 'is fut…. Ma'ra t' fur way…"
"Hashirama!" Izuna yelled out as Tobirama started to lean on him for support, fighting back the black spots in his vision.
"Otouto-!" Hashirama gasped, taking in his brother's condition and began pushing healing into the wound to at least stop the bleeding.
"You!" Madara bellowed, "Why would you do such a thing for an enemy?!"
Tobirama coughed again. "'Cause, you two weren't the only ones who made a friend you shouldn't have at that river…you two were just the ones who kept going to the same spot and got caught." Tobirama grabbed his brother's hands and slowly formed a few seals using them in the way he usually did when he was showing something new to his brother, who was currently looking at him concerned.
Hashirama looked like he was going to protest but nodded with tears in his eyes.
"Izuna, you'll need to pull the katana out. Madara, you'll need to cauterize it with a precise stream of fire. Use horse-bull-snake and focus to make it thin."
"You know fire justu?"
"Izuna needed someone to practice with when you were busy. Now, hurry of the jutsu I just showed Hashirama will not have any chance."
"Just showed?"
"One I have been experimenting with. If it doesn't work, I die either way."
"Please, my friend… my last brother." Hashirama said, more tears flowing, emotions true.
Madara nodded and on the count of three, a yank, a push, and a burn was felt all at once.
Then the world went black.