Normal POV

Natsu starts to grow black horns as Zeref smiles from a distance. "Welcome back END. " END growl, glaring at him. "I'm going to kill you this time." END grins pointing at him. In a flash he was already behind Zeref swinging a fist burning black, slamming it into Zeref. Zeref bearly block as he was pushed back a little. "Heh, starting off strong already. How long will it take before Natsu gains control again?"Zeref asks with a grin, pissing END off once more. "Shut up. This is my body.You created me using it." Sending a swarm of black flame punches at him.

Inside Natsu's head

Natsu continues to attack the bars of the cage. "Let me out!" he shouts, his flames becoming more violent. "Natsu, why don't you sit back. "a voice grins beyond the bars.

Natsu's POV

"Natsu, why don't you sit back." a voice calls to me beyond the bars. "Show yourself!" I demanded. The person turns out to be...me with a black scarf? "Who are you!?" The other me lunges at me and grabs my arm and back of my neck. "I'm you of course. But unlike you, I know the power of demon magic." he grins pulling me closer. His fangs making me uncomfortable. I burst my body into flames and he leaps back, still grinning. "So now you're ready to fight?" He questions,his killing intent bursting crimson. His dark flames devours his body only leaving his sinister smile and demon eyes glowing expose. "I'm fired up,Natsu!" He laughs,mocking me as he disappearing into the shadows.

I looked around trying to pick up his scent. Nothing? "What's wrong,Natsu? Dragon magic failing you?" A voice whispers into my head. Something burns into my back, it's claws digging deep into my back. My body was slammed into the bars of the cage crating a crater underneath me. I couldn't move. "Just give up and let me take over,dragon breath." His head leans into the edge of my eyesight, grinning. "Never!"I burst into flames trying to throw him off me.

The other me leaps back. "Stop being stubborn already. It's annoying."he mutters. "Then you don't know me." I grin swinging a Iron Dragon fist. He grabs my fist and dig his claws into to it,drawing blood. I leap up and spin kick his face til he stumbles back. He wipes something from his mouth, glaring at me as I charge towards him with a Fire Dragon Crushing Fang, leaving a flurry of flames in my wake as I land behind him.

However looking back, the other me grins getting back up and creak his neck. "Is that all you got dragon boy?" What? Not even a scratch on him. "If so, then it's my turn." His fist burst into black flames in the shape of claws as he makes his way toward me. He claps his claws together and once they came apart, a ball of black flames forms in between. He throws it towards me and I dodge it with ease, but he disappeared from my view.

I continue to look around and listen for him. A footstep come from my right and on instinct I swing towards the sound with a Fire Dragon's Flame Elbow, propelling me in that direction. "Missed me." A laughter hits my ear before an burning elbow strikes my back, crashing me into the floor. "I thought you were gonna kill me,Natsu? Isn't that what you told Zeref? " he laughs standing in front of me. I growl before blasting out a Fire Dragon Roar towards his face."You're. ..END?" I looked at him with disbelief as he recovers with a grin. "Oh so you finally figured it out. Congratulations Flame brain." He claps. Now I'm really fired up, now that I know who this person really is. I grin as my body burst into flames, heating the area around me.

I ignite my fist and charged towards him entering into Crimson Lotus: Fire Dragon's Fist. I swing my fists with a barrage of punches aimed at his face and stomach. Explosions with each contact as I manage to push END back. I end with Crimson Lotus: Exploding Flame Blade, slamming him into the wall in a crater.

I pant as he slides down the wall and slowly gets up. He coughs up some blood and spits the rest on the floor.That must have done it.Then he burst into laughter. "Just kidding." He reveals a pack of fake blood in his hand. "I congratulate you on actually hurting me however."he grins pointing to the large cut on his cheek. I growl but then a sharp pain strikes my whole body. "I forgot to mention. Every time you hurt me, it's hurts you. " he grins."We're connected. You and I." He grips the collar of my shirt, burning it as he ignites his fist. I grab his wrist and glare at him. "Just give up and let me take over. It's my turn for once. " he whispers in my ear.

I entered into my Lightning fire dragon mode, sparking him with lighting infused with fire magic. I blasted a Lighting Fire Dragon Roar at him, pushing him back. "Ah so dragon boy got new tricks. "He grins getting excited. "Show me your best." I made the first move and charged up my fist.

Zeref's POV

I grin looking at the wounds, flames bleeding from them. "Is that all you got!" END shouts charging towards me with flaming claws, burning everything in sight. He swings his hand making the flames extend and grab me. END throws me through the forest, which is now engulf in black flames.