What would have happened if Kakashi had been standing just a little to the left during the cave-in? A series of moments in the lives of Uchiha Obito and Hatake Kakashi.
Obito saw everything in shades of red through the sharingan- Rin's hair appeared black, and the smirk on his enemy's face was blood-colored. There was only the one Stone nin left, but he was more worried about the way Rin sat against the rock wall, unresponsive. Her chakra moved in strangely, swirling in on itself in random patterns. He glanced at Kakashi; his chakra moved in steady lines of force, uninterrupted and strong. Obito felt another stab of worry for his teammate.
"The flow of Rin's chakra is pretty unstable; it's different from ours."
"It's probably a genjutsu; he must be trying to extract information." Kakashi, even injured as he was, kept his cool under pressure- as usual. Obito was too charged with adrenaline to feel annoyed at his attitude. "Be careful against this guy; we got lucky with the other one. Be fast and don't do anything stupid."
"Gotcha!" There was no time to worry now; Obito fell into a battle stance and launched himself at the enemy ninja. He could see the path of the man's movement playing out in potential chakra patterns- it was child's play to counter them. Kakashi leapt in over him as he blocked the enemy's arms with his feet; the stone-nin went down beneath Kakashi's blade with a short scream. Awesome! He gave himself a mental pat on the back, flipped backwards onto his feet, and rushed to Rin's side.
She stared up at him blankly, and her chakra surged sluggishly.
"It's just a genjutsu. Watch- kai!" Kakashi released her from the genjutsu with a simple hand seal. "Rin? Are you okay?"
She blinked rapidly a few times and smiled up at him. Obito felt his heart clench, but his smile didn't waver. "I'm fine. You came back for me, Kakashi-kun..."
Kakashi stiffened and pulled away, uncomfortable with the open affection on her face. "Don't thank me." He jerked his thumb at Obito. "He came back for you. I just went along to keep my team together."
He snorted, and readjusted his goggles. Trust Kakashi to be an asshole about saving her- but he wasn't going to argue when it made him look good in Rin's eyes. She turned to him with a grateful nod. "Thanks, Obito-kun."
He grinned and gave her a thumbs up. It still hurt that she turned to Kakashi first, but he couldn't blame her- in her position, he'd have done the same. He's an arrogant asshole, but he's a damn good shinobi. "Hey, any time! I got my sharingan- it looks like this is going to be my lucky mission!"
Kakashi rolled his eye, but he looked more amused than anything else. "That remains to be seen. We need to get back on course before-"
Obito saw the sudden shift in energy around them, felt the ninjutsu happening- but not fast enough to react when he heard the voice of the Stone nin growling behind them.
"Buncha punk kids aren't gonna take me down! Doton! Iwa Yado Kuzushi!"
The ground trembled violently, knocking them all to the ground. "Shit!" Obito staggered to his feet and turned to check on his teammates.
"Come on! Let's get out of here!" Kakashi helped Rin to her feet and gave her a shove. "Go!" They raced towards open ground as the rock wall began collapsing around them. Small stones and pieces of debris rained down on them while the quake increased in strength- in a moment, the entire cliff face would be on top of them.
Obito heard Rin cry out when Kakashi stumbled; he skidded to a stop just as a boulder the size of a horse crashed into the ground nearby. Kakashi was on the ground, stunned- he must have been hit in his blind spot. Damnit, that's my fault, he wouldn't have gotten hurt if I hadn't needed saving! More rocks were falling, and Kakashi wasn't moving. Obito didn't even think before he leapt- he never did- he just ran to his teammate's (his friend's) side.
"Kakashi! Come on!" The rocks gave another ominous crunch, and Obito was thankful that Kakashi was smaller than he was as he threw the other boy out of the way. There was another thunderous rumble, and then the only thing Obito could see was dust and rock. Then he was blinded by debilitating pain, and momentary blackness. The silence that followed was worse than the roar of falling rocks.
He cleared his throat; there was dust in it. "Guys? Are you okay?"
A tiny chakra-lamp lit up Rin's sweaty, grimy face and Kakashi's silhouette beside her, casting shadows on the rocks and rubble around them. They were completely caved in. "I'm okay. Are you- oh, no." Her voice died in her throat and her face went pale beneath the dirt. "Obito!"
He managed a weak grin. "What? It can't be that bad. I'm okay, just a little stuck." He tried to laugh, but ended up coughing instead. His right arm was trapped beneath a pile of rubble, but he could still wiggle his fingers a little- if he felt like blacking out again, that was. He couldn't feel his right leg, but he could see the boulder that had landed on it, and that worried him a little.
Kakashi was at his side in an instant. "You idiot. Why did you push me out of the way?" Kakashi loomed over him, looking upset- really upset, not just pissed off. He began pawing at the rubble that trapped Obito's arm.
Kakashi was very smart, Obito reflected. A genius, certainly. But sometimes he was a complete and utter moron. "You were going to get hit by a giant boulder. Why else would I push you out of the way?"
He didn't really expect Kakashi to react by staring at him with a stricken expression out of his one eye. "You- this is my fault. I should have- if I hadn't- I-"
"Move, Kakashi, let me look at him." Rin had recovered from her initial shock and had gone into full medic-nin mode. "Obito-kun, give me your status." She pushed Kakashi out of the way and ran careful hands over his chest, checking for fractured ribs. "Are you breathing okay?"
"Just some dirt up my nose. I think my shoulder's dislocated, and my arm might be fractured. Hurts like hell, but it's still there...can't feel my leg at all."
He felt her hands moving with clinical detachment across his shoulder and at his hip; his vision swam, and he heard someone screaming. "Kakashi, put something in his mouth, I'm going to put a tourniquet on his leg." Sensei's kunai had canvas wrapped around the handle; it tasted like metal and sweat, but it gave him something to scream around as Kakashi dug out his arm. The pressure on it eased as the rubble cleared, taking some of the pain with it.
"Just dislocated and a bad sprain." Kakashi's voice was gruff; he sounded more like himself, now. "Bite down." His shoulder popped; he screamed around the kunai in his mouth, short and shrill. Then the pain eased to a dull throb, and Kakashi took back his kunai. "There. Rin, his leg...?"
Her face appeared in his field of vision, tight and worried. "It needs to be amputated." She kept up her professional face for about half a second before she lost it, rubbing furiously at the tears that suddenly spilled down her cheeks. "Obito-kun, I- I'm so sorry, it needs to be done, we can't get you out any other way, the boulder's too big to move and the damage would be too extensive anyway. And I can't give you anything for the pain when you've lost this much blood..."
He closed his eyes. The sharingan had activated again from the pain, but he couldn't afford to lose any more chakra. "Don't bother. You guys are still okay- you need to get out of here. You have a mission to complete, and that guy up there is probably getting reinforcements. Just- just leave me here. Thanks for getting my arm free, but, you know, you don't have time to waste. Kakashi, I want you to-"
"Shut up." Obito's eyes snapped open. Kakashi shoved the handle of his kunai back into Obito's mouth, one eye narrowed angrily. "Just- shut up. I'm this team's leader, and I decide who gets left behind. If I'd gone with you from the start this wouldn't have happened, and I'm not making the same mistake again. Rin!"
"Yes, sir?" She clung to her professionalism with a trembling voice- but her hands were steady.
"Do it quickly."
"Yes, sir." Her fingertips glowed with concentrated chakra. "Keep him still."
No! He tried to struggle, to push her away- but Kakashi was holding him down, and refused to look him in the eye. He would rather be dead than a cripple- without his leg, he would be useless as a ninja, and he'd had enough of that already. He was enough of a disgrace as it was- his family would approve of him dying with honor, his teammates couldn't do this to him- and then Rin was slicing through his leg with the equivalent of a chakra bone saw and all he could think about was the pain and the smell of cauterizing flesh.
Reality became flexible after that- the pain went on and on, even after Rin finished bandaging the ruined stump of his leg, and the taste of sweat, metal, and blood lingered in his mouth. Kakashi barked orders, shouted things, and there was a response from somewhere. Obito was lost in a chaotic swirl of pain and distorted sensory input as Rin fed him chakra and medicine to stabilize his wounds; he might have been screaming. At some point, a shaft of sunlight hit his face, blinding him.
Sounds bled together- the rumble of rocks falling, Rin screaming, and the chirping of a thousand birds.
He thought, in a detached sort of way, that those sounds were going to haunt him for the rest of his life.
He was right.