A/N: This is a quick chapter to explain why, in the last chapter, three Hokage, Mito, and Madara didn't stop Orochimaru and why it stuck so close to cannon. Hopefully this isn't too out of character for Hiruzen, and clears up some of your questions!
As he prepared the Reaper Death Seal, Hiruzen looked over at his once student. Orochimaru seemed to still be in great fighting condition, as did Tobirama. But his sensei appeared to be holding back, probably knowing that Hiruzen wanted to be the one to land the final blow. Orochimaru was his student, and Tobirama respected his unsaid wish to deal the final blow. But as Hiruzen stared over at Orochimaru, hands shakily making their way through the painful seals that ended his successor, he felt his heart clench, much like it had all those years ago, when he first had the chance to end his student. He grit his teeth and started on the final string of seals.
"Enma! Now!" He shouted, shooting forwards towards his student, as his monkey summon slammed Tobirama away from the battle. As he had hoped, Tobirama landed a significant ways away from him and Orochimaru. Hiruzen latched onto his student, ignoring the blade that nicked his side when it dropped from Orochimaru's grip. "This is it Orochimaru!" Hiruzen growled, as he activated the jutsu. "It's over! Reaper Death Seal!" He felt chakra gather behind him, before something freezing cold shoved its way through his abdomen and into his student's. Orochimaru started to struggle, but Hiruzen held tight. His heart clenched once again when he spotted the fear hidden in his student's eyes. He felt his soul being tugged out behind him, and, with a glance down, he knew that the snake's soul was being pulled out as well. He tightened his grip as the Sannin's struggles became worse as he glanced down as well. His student started trying to pull his soul back in, his hidden fear now clearly displayed, and hissed and growled at him, though Hiruzen didn't pay attention to the many death threats coming from him.
"Sensei! What are you doing!" Orochimaru whispered, barely loud enough to hear. Hiruzen's heart felt like it was tearing into itself. But then, as his student called him sensei out of fear for his life, he realized something horrific.
He couldn't do it.
He couldn't end his student's life. He couldn't do it back then, and now, when he had the perfect chance because he wasn't exhausted yet his student was, he still couldn't. But it wasn't like he could stop his jutsu. He glanced down at the soul in between them. There was one thing he could do. He could stop Orochimaru from ever destroying anything ever again.
"Orochimaru... if I can't take... your whole soul..." Hiruzen gasped, staring at his now frantically struggling student. "I'll just take your ability to use jutsu away from you!" He felt a shift behind him, and then his student and Tobirama screamed at him, and Orochimaru's hands fell useless to his sides, slowly blackening. Hiruzen let go of Orochimaru and staggered back, before beginning to fall to the ground. He was caught before he hit the ground. He vaguely heard Orochimaru calling for retreat. Tobirama stared down at him, scolding him for his stupidity. "Sorry... sensei... but I'm..." He took a breath, and smiled a bit wider at his sensei. "...finished... I'll see you... again... soon..." He felt his eyes slide close, and the last thing he heard was a soft sigh above him.
Tobirama sighed as Hiruzen's eyes closed. He gently lay the man down on the ground, and whispered a soft prayer for him. He heard feet pounding towards him, and he began to neatly arrange his once student's body into a neater position, more befitting of the dead.
"Tobirama... Hiruzen's...?" His brother asked, sorrow clear in his tone. Tobirama nodded, and stood. He turned to face the three behind him.
"Yes. The Third Hokage has fallen in battle." He said, ignoring the ANBU who rushed forward. Hashirama stared down at the smiling body, and leaned onto his wife.
"We should have been there to greet him in the afterlife..."
"Where is Orochimaru?" Madara asked, changing the subject, knowing that Hashirama might go into a depressed state at this rate. Tobirama tensed and looked around.
"He was right there. He called for a retreat, but his lackeys couldn't have gotten him out before the ANBU arrived. They were right outside the barrier." Tobirama sent out detecting chakra, prodding close signals. Madara's Sharingan whirled to life, morphing quickly into the Mangekyou, and he looked around, analyzing what little chakra in the air he could.
"There was a transportation jutsu used. One similar to the Body Flicker, only it was used for multiple people at once. Four in those corners," He pointed at the corners of the roof. "and one for right next to Hiruzen."
"That was Orochimaru. Can you tell where they went?" Madara shook his head.
"Whoever set this jutsu up, they must have had extensive knowledge of the Sharingan. I can't tell with the regular Sharingan, but with my Mangekyou, I can say that they went somewhere to the east. After that, I'm afraid that the trail is gone." Madara said, turning to look in the direction he claimed. Hashirama tsked from beside him.
"So we can't even get even with the brat for Hiruzen's death." Hashirama muttered, prompting a raised eyebrow from his brother.
"Hashirama..." Tobirama walked up to his brother, and patted his shoulder. "Next time brother. For sure."
