Dragon? Demon? Both?

Visited by a Fire Dragon

(3 days later, 30 miles further north)
    Over the last few days, Lucy and I have tried to hide that we just got together from our 5 other team mates, however, we got found out literally the next morning. Lucy was on guard duty last and I've been waking up sooner than normal, like 6:00 early. Anyway, I had been warming up a cold Lucy when Happy found us with a "They liiiiiiiiiiiiiiiike each other" and I responded stupidly, with a "no, I love her, and she loves me back" causing Lucy to become a blushing mess, other than Erza threatening me with pain if I hurt Lucy, the rest of the day went uneventful.
    Returning to the present, it was around Noon on our journey north we heard a dragon's roar. Sniffing the air, I got a whiff of a very familiar scent, but it was different, Lucy, Erza and Gray were all on edge. Wendy and I however, we were a little surprised, cause the scent was closing in on us fast, faster than Acnologia "Wendy get back, this one's mine" Wendy nodded and backed up with the rest of the group.
    It was only a couple more minutes before the dragon came into sight. Once it got to us, it landed right in front of me "I finally got to meet you" I smirked "would I be correct to assume that you are the dragon that wishes to fight and kill me." the dragon chuckled "as long as I am correct that you are Natsu Dragneel." I nodded affirmatively, shifting my weight slightly to the right "what's your name, I will not fight someone who I don't know the name of in a death match." The dragon was kind enough to respond "my name is Ignia, Fire Dragon, Son of Igneel." (look up Fairy Tail Ignia for what Ignia looks like.)
    "I am Natsu Dragneel, Fire Dragon Demon, Son of Igneel, successor of Igneel, Inheritor of the apocalypse element, Fairy Tail mage." Ignia raised his eyebrow "other than somehow having my tattoos, you don't look like much." I chuckled "Let me show you something."
(Listen to Natsu's theme)
    I started to power up, slowly growing larger, until I was a dragon slightly taller than Ignia, my scales were crimson red with a cyan flame design, my body shape was almost exactly like Igneel's, I had slightly more deadly looking wings and a bladed tail. My scars carried over to my dragon form, my iris' were gold in color, I also had horns like Igneel. I looked at Ignia, he was shocked at my transformation "shall we begin?" Ignia smirked "about time!" I instantly went in for the attack, engulfing my left claw with dragon fire and uppercutting Ignia's gut, sending him into the air. Ignia sent a roar of fire at me, I flew straight up, through the fire and got on Ignia's level "it hasn't been 2 seconds and I'm already bored."
(Listen to Dragon Force)
     My body glowed a red and purple color, slowly shrinking down. When the glow died down, I was back in my human form, however, I had activated Dragon Force, my shirt was missing but I felt it in my requip space, the scales were a crimson red, my tattoos were part of the scale pattern, I rushed Ignia again "Fire Dragon King's Demolition Fist" my right fist was engulfed in golden fire. I uppercut Ignia, making him growl in pain, he made the mistake of using his breath on me. His flames were red with a black layer on the outside, I hovered there, waiting for the flames to come to me. When the fire reached me, I ate them, and as I did, my scales started to spread, scales covered my arms, my lower legs were also covered in scales. 2 horns sprouted from the top of my head, they were 9 inches long, 2 inch diameter at base (Half dragon mode horn design) When I finished eating I glared at Ignia "thanks for the meal" I charged him "Fire Dragon King's Blade Horn!" I slammed into Ignia's gut, my horns impaled. Ignia roared in pain, I lifted my head up, making the wounds larger. Ignia grabbed me and threw me into the ground.
Standing up fairly unscathed, I launched myself at Ignia again, I engulfed my fists with fire, it was Ignia's fire, I flew past him "Fire Dragon King's Incinerating Flame!" I put my fists together and slammed them downward, sending the giant fireball at Ignia, engulfing his body completely. Ignia roared in pain, eventually, the flames died down, revealing a severely burned, and mostly scaleless dragon. Engulfing myself in fire, I flew under Ignia's head "rest in peace." I flew upward, through Ignia's skull and out the other side. Ignia's body slowly fell from the sky. Shortly after it landed, I crashed down next to his body "what was the purpose of challenging me?" I waited, after hearing nothing I sighed and walked up to the slowly disappearing corpse and the pool of blood. Wading through the pool I heard footsteps behind me, looking back I saw Lucy and the others running up to me "don't enter the pool of blood!" Everyone stopped at the rim, Lucy looked the most worried about me "why not?"
"Dragon blood is magically corrosive, instead of melting your flesh, it melts your magic, Dragon Slayers are only immune to this because of our unique magic." Lucy nodded, I continued wading through the blood to the center. Once at the center, I activated my dragon slaying magic, the blood rushed into me, slowly increasing my power once again. Once I finished absorbing the blood, my power had Increased by 50%. The moment all the blood dissapeared Lucy slowly walked towards me "Natsu? Are you ok?" I looked at Lucy and smiled "of course I'm ok Lucy." I deactivated Dragon Force and walked to her. I requiped my shirt back on and kissed her cheek "come on, we have a dragon to hunt that is to the north" smiling I turned around and started walking north with everyone behind me.
I heard a faint whisper of Ignia's voice "all hail the dragon king."