Kakashi POV~

I hit the ground hard, the impact knocking the wind out of me and jarring my bones. The fall wasn't as bad as it could have been, my Shinobi instincts automatically urging me to drop in a roll, but that wasn't what hurt the most.

When I did a quick scan of my surroundings, it was obvious to see that I was in the space-time dimension of the Kamui. I figured we were connected to the same time-space, this only proved it.

For a few minutes, there was nothing. The air was breathable here, obviously, but there was dead silence. None of the background noises of our world. 

Naruto spent a whole day in here. Not for the first time, I was glad he had Kurama with him.

I waited, taking this time to catch my breath. I did a quick scan of my wounds, patched them up rapidly, and stayed put in a crouch.

The few minutes I spent in the complete, unnerving quiet were heavy. The silence weighed on me like a thick blanket, and I didn't dare move a muscle. 

Then a shuriken clipped past my ear after I managed to narrowly avoid it, and he was here.

Naruto POV~

Obito was quick to send Kakashi to the Kamui realm. That alone sent anger shooting through me.

Sasuke and I grew relentless in our attacks, Kurama's chakra swirling and flickering across the whole area. We were all in perfect sync, none of us having to say anything to understand each other. We dropped into a rhythm, then, matching blow for blow, strike for strike. Each attack that I launched was immediately backed by Sasuke, and Kurama provided defense for all of us, allowing no blind spots in our formations.

This alone, along with the Konoha twelve surrounding the perimeter and Gai's blinding speed to watch out for, pushed Obito into a corner far enough that he retreated to the Kamui dimension himself.

He didn't come back for several long minutes. 

When he did, everything went to hell.

Kakashi POV~

Obito and I faced each other, alone for the first time in years. But this was different. The situation was different, he was different.

What happened to you, Obito?

I felt it forming, the horribly familiar crackle of electric chakra racing through my arm and forming on my hand.

First chance I got, I drove it towards him. The lightning blade stopped only inches from his face.

Obito was looking up at me, his eyes cold and shadowed. With a faint smirk, he said, "There's still doubt in your heart. You've had several chances to kill me before. Why didn't you?"

I stayed silent, the Chidori still on my fingertips.

"Is it guilt, that you couldn't protect Rin? Or keep your promise to me?"

My already shattered heart was getting kicked even harder with every word. "Obito...stop this already - "

Before I finished, though, he stood. I couldn't stop the Chidori in time, and he walked right into it.

I froze, a terrible chill going straight down to my bones.

The same thing...

The blood won't wash off.

It never washes off.

"I know everything." he said, his tone growing harsher with every word, "I know Rin deliberately ran into your Chidori. But nothing you say changes anything. To me, you're still an imposter who couldn't protect her."

His face darkened. The shadows seemed to come alive, deepening the lines of his scars and wrapping around us, tightening and choking -

"Obito," I stared into his eyes, locking into his gaze, "Don't you remember what you told me? About - "

"Look!" he shouted, suddenly and violently. His voice tore into me like a knife, edged with a slicing blade. He stepped back, gesturing at the hole in his chest, "There's nothing in my heart!"

I could only stare, everything he said sinking into me like tar.

"Don't feel so guilty Kakashi." he gestured to my sides, "Rin is here, along with your ideal version of me."

A young Rin, along with Obito as I once knew him appeared on either of my sides. Again, I felt the Chidori forming on my hand, and I sliced across the air, destroying both genjutsus without another look at them.

"Rin is gone!" my voice came out even and hard, "But you're still alive. You can try to fill that hole in your heart with delusions, but nothing will fill it!"

A growing anger, a frustration, began to bleed into Obito's voice. A darkening pain began to take shelter over him.

"Reality is cruel. Things don't always go how you want. Like it was with me." he grit his teeth and looked away, "Like how I couldn't get there in time."

Silence between us. The air, heavy and still without wind in here to move it, grew unsettlingly weighted.

I felt more grounded than I have in a long time when I said, "I may be trash as a shinobi, but I've learned a few things. In the ninja world," I looked up and locked gazes with him again, "those who break the rules are scum."

I felt as if a wall was crumbling within me, a wall that held me back for so long, the pressure of Rin finally lifting after so many years of being unable to breath. "But those who don't care about their friends? Are worse than scum."

The line between us snapped. A Chidori was on my hand again before I knew it.

"I won't abandon my memory of who you once were."

That broke it. Without a second to spare, we clashed.

"Enough of this. No more genjutsu, Obito."

Our genjutsu selves dissolved in a crackle of lightning, and once again we were facing each other.

"Right now, the only thing I can give you...is death." I raised my hand, forming a hand sign as I did.

Obito narrowed his eyes slightly and did the same. "If that is the case, then I will too."

A beat of silence. Then, we ran at each other, and the fight began.

We matched each other with every blow, every hit. I tossed a kunai in the air, holding him off until I spun and kicked it blade-first toward him. He turned just in time, the edge nicking him in the cheek.

Each attack held years of emotions, emotions left bottled up within both of us. Each punch was bittersweet, each kick holding memories of previous spars. Different spars, with a different Obito.

A fireball jutsu was shot towards me, and I blocked it with an Earth Style: Mud wall.

We were sparring on the field of the training ground, Rin cheering us on and Minato sensei observing from the sidelines.

A flash of movement to my side made me turn toward it on instinct, but it was just a piece of cloth tied to a kunai, a decoy. I whirled around, a kick colliding with my head and smashing me into the wall I created.

I blocked his fireball with a Mud wall. 

Blinking spots from my eyes, I hid the shadow clone beneath the ground. It exploded from under his feet, grabbing Obito and blocking him from my real body.

"The real one is here."

The clone disappeared and in its place was electricity. With a yell of pain, Obito fell backwards, unable to roll away from my next kick. It sent him flying backward, rolling to a stop several feet away with a pained gasp.

We leaned in towards each other, each holding out two fingers for the unison sign.

I banished that memory, charging a kunai with Chidori. We ran towards each other, and it hung in the rapidly closing gap between us.

Obito.

I lunged forward just as he did, lashing out my lightning-charged kunai as he formed another black stake in his hand.

This is all I can do now.

Our feet landed on the ground at the same time, throwing up a cloud of dust and echoing in my bones and the silent air. 

By killing,

We lunged toward each other, aiming straight at the heart.

The current Obito.

Silence. 

Then, a choked gasp as Obito struggled to maintain his breathing. He gagged, coughing up a mouthful of blood.

I hated this. I hated this.

My eyes were squeezed shut, my forehead creased and my whole body trembling. My hand began to shake, and the kunai slipped out of my hand and clattered onto the ground. The sound echoed in the vast quiet, as loud as shattering glass.

I'm sorry.

I was, but I wasn't. I didn't regret this. If this was the only way I could save everyone, save Obito, then damn it all, of course I did it.

I forced my trembling hand into a fist and yanked backwards, pulling out my arm in a one swift motion. The whole thing was coated in blood. Not an unfamiliar sight.

Obito fell backwards, his back hitting the ground heavily as he sucked in a wheezing breath. He hissed as he struggled to stand. I didn't have it in me to push him back down.

My arm covered in blood (Obito's blood) hung limply at my side. I straightened as best as I could. My chest ached at the sight of him, but it was done. It was done.

"It's over, Obito." I said, my voice small and weak, yet still sturdy.

He gulped in air heavily, his body heaving in the effort of taking each breath. He glanced up and looked at me, eyes shadowed with pain. Blood dripped down his chin. There was a hole in his chest around where his heart would be. A real one, not a genjutsu this time. This one was leaking blood, too much blood to be survivable. 

Somehow, he gathered enough energy to say, "I'll let you have," another struggled intake, "this victory."

Then, with his remaining, fading chakra, a Kamui swirled to life in his eye and he vanished back to the real world.

When he was gone, the silence fell again, deep and burdensome.

I fell to my knees, the only sound being my labored breathing, and choked sobs that would never reach daylight.