In a world full of ninja and specialized powers that involve a spiritual energy known as chakra, war still wages. No matter when or where humans always resort to violence, as it's the only thing they truly understand.
Most of the time it's between adults, but sometimes the adults have no choice but to use children in their wars. One such event led two bitter rivals to finally understand each other, the son of the White fang and the Black sheep of the Uchiha.
Kakashi Hatake had saved Obito from an invisible Shinobi from the Hidden Stone, but it cost him his left eye. Things were dire until Obito awakened his Sharingan and stabbed the stone Shinobi with a kunai. Afterwards Obito helped patch up Kakashi's eye injury with a medkit Rin gifted to Kakashi for his promotion to Jounin.
When it was done they ventured into the cave and saved Rin after defeating another Stone Shinobi, but the Shinobi wasn't killed. He decided to collapse the cave with the three kids inside.
The three rushed to the exit with rocks and boulders crashing down, narrowly missing them. But someone wasn't so lucky, a pebble hit Obito on his head, dazing him for several moments, even the Sharingan couldn't predict this. Kakashi turned around and saw that a boulder was crashing down toward Obito. Kakashi's body began moving on its own, he ran toward Obito and tossed him out of the way and to the exit with Rin. But in return Kakashi didn't have enough time to move out of the way.
With the collapse of the cave a dust cloud came over the area. Obito coughed as the dust invaded his nostrils, and when he stopped, Kakashi was the first thing on his mind. "Kakashi... Kakashi!" He yelled out, hoping Kakashi was okay.
"Obito..." Kakashi said weakly from Obito's left. Obito turned and saw Rin kneeling next to Kakashi, who had the right side of his body underneath a large boulder. Obito walked over and could see the tears dripping down Rin's face. Obito couldn't tell but he himself started crying at the sight of Kakashi.
"Obito, stop being such a cry baby. The Future Hokage shouldn't cry, he should be strong..." Kakashi said, even though he couldn't see he just knew that Obito would cry.
"But Kakashi, you're..."
"I know... But at least I can't feel any pain... The entire right side of my body is numb..." Kakashi said. It was almost like he was happy.
Obito felt like he was powerless, he wished that if anything he had saved Kakashi instead. "Kakashi, we'll try and get you out. We'll take you back to the village and they'll..."
"Don't bother... I'm as good as dead... Just get back to Minato-sensei and complete the mission..."
Rin was just left speechless, the boy she had a crush on had just told them to leave him for dead. How could she even react? Surely there was something she could do, she learned medical ninjutsu for a reason. But neither she nor Obito would be able to move the boulder.
Obito begrudgingly knew that Kakashi was right, there was literally nothing they could do to help. "Kakashi, I'm sorry for how I've treated you. I just always thought you were the coolest, even if you were a little stick in the mud."
"Obito, promise me you'll protect Rin and fulfill your dream... by becoming a great ninja..."
Obito nodded, "I will. I promise you won't have died in vain."
"At least I can meet my father again... Maybe I did him proud..."
Obito was filled with a burning resolve to protect his comrades, and fulfill his friend's dying wish. He stood up and jumped up out of the pit they were in and saw that they were surrounded by a battalion of Stone Shinobi. Obito no longer felt fear in the face of danger, he only knew he had to protect Rin from danger.
Rin felt rumbling and understood that the Stone Shinobi were going to cause a sinkhole that would kill her and Kakashi, Rin didn't have enough time to get out but Obito grabbed her and pulled her out of the pit. They were on top of a rock facing the battalion. As they were on the rock, Rin noticed that tears weren't falling down Obito's cheeks, it was blood.
Obito rushed head first into the battalion and utilized his small stature and Sharingan to his advantage. He killed man after man, covering himself in blood, ensuring that Kakashi's death wasn't for nothing. As Obito was about to charge the last man, he went through the last Stone Shinobi had actually stabbed Obito but nothing happened. The man was then hit by a rasengan.
Minato had arrived late but he was dead terrified of Obito's fate and he inspected Obito but he was perfectly fine, not a single injury. It was strange, Minato swore he saw the sword in Obito's chest. But then again Obito was covered in blood and yet he was unharmed.
Obito felt weird though, he knew that sword went through him but nothing was there. How could that happen?
But then Minato looked at Obito's eyes and saw something strange, they were Sharingan but they looked like shurikens. Minato wanted to learn more but he needed to check on his students.
"Minato-Sensei, Kakashi risked his life saving me. But he..." Obito tried explaining but the words could no longer come out.
Minato placed a hand on Obito's shoulder, giving him a solemn look. "It's okay, it's my fault for not having been there." He gave a look of understanding, to try and calm his student's nerves. "On the battlefield nothing is certain, especially if you'll return home. And as a teacher it's my duty to watch over and protect you three... two. I failed, not you." Minato began walking away, "But we can't let his sacrifice be in vain. Let's complete our mission."
The three mourned Kakashi's death but persevered and headed to complete their mission to destroy the Kanabi bridge.
Team Minato completed their mission and returned to the Leaf. There was a funeral arranged for those who died that day and a fire shrine where Kakashi Hatake's name had been carved. Obito placed Kakashi's chakra saber below the shrine, to pay respects for his friend and the White fang.