Alex explored the northern parts of Alakitasia for the better parts of an entire week before he started to notice a faint, but familiar, scent in the air. He had been keeping to regions devoid of people, from what he remembered of the calamity that was Acnologia, the dragon hated people and saw them as less than bugs. It was with this in mind that he chose to search the secluded areas first.
Focusing on the scent in the air that seemed somehow familiar, Alex couldn't place where he knew it from, it reminded him vaguely of Wendy for some reason but he quickly shook that feeling off. It didn't make any sense. Focusing on the sensation with his mana-sight, he realized it wasn't a physical smell but a magical one. This narrowed his search quite a bit and the connection with Wendy also made a bit more sense, though she wasn't the only one.
"First gen. Dragon slayers? Huh, I wonder why I never made that connection before", Alex mused to himself. The 'scent' was the same one that seemed to linger around areas where his friends, who use Dragon Slayer magic, cast a lot of spells. The guildhall is positively drenched in the smell, so it has never stood out.
Playing a hunch, Alex followed the scent. Knowing the only thing that could possibly smell like a Dragon Slayer, that would be in this area should be Acnologia, Alex also entered Stealth. It took two more hours of slowly moving through the mountains before he found a cave. It was too small for a dragon and Alex was about to dismiss it. Deciding to air on the side of caution before he left the place, he sent a pulse of magic into the cave to see how far it went or if it was occupied. To His surprise though, there was a human inside. It surprised Alex more that this human didn't have a physical smell, than the fact that there was a hobo living out in the boondocks. He was going to go ask the guy what his deal was but was stopped from entering the cave when that man bolted out of the cave and started furiously scanning the surrounding areas.
'Holy shit. He must have good magic senses to be able to feel that light magic. ...wait, why does this guy look familiar?" Alex wondered. The man was dark skinned and topless. He had messy dark blue hair that hung well below his waist. He was well built and had strange blue markings on the parts of his arms visible under his heavy black cloak. An intense gaze slowly scanned the area before the man started releasing his own pulses of magic.
Alex kept staring at the man trying to place where he knew him from but in the end he couldn't. The pulses of scanning magic started getting more intense and spanning further, but Alex ignored them, they had no hope of finding him so he wasn't worried about it at all. Alex was about to carry on his search for the elusive black dragon when he felt a colossal amount of mana leave the man's body. He hadn't been able to sense even an eighth of this amount of magic from the man and it grabbed his full attention. The markings on the man's skin started moving across his body as his limbs started elongating. Before Alex's eyes, the man transformed into the very Dragon he sought.
"Acnologia", Alex mumbled under his breath. He tried thinking back to his past life to see if he could remember any of the details about the dragon's transformation, but the memories were vague and unhelpful. 'Doesn't matter I guess. I found my quarry', Alex realized.
Not willing to let the newly transformed dragon take to the sky, Alex withdrew both his glaives and leapt into the sky. With a flap of his wings propelling him downwards, he drove both of his magic blades into the spinal area of the dragon. Quicker than Alex thought would be possible, Acnologia released a concentrated blast of magic from his back that not only pushed Alex off of him, but kept the fel-fire within the blades from being able to latch onto his body.
The massive black dragon spun around a few times while it's wound was glowing with a greenish-blue light. Not being able to find the insect that had 'stung' him, Acnologia started blasting the area around him.
Having been forced to the sky, Alex dashed toward the dragon once more, this time stabbing one of his blades into the dragon's left eye. Again, faster than Alex could match, Acnologia retaliated. Blindly swinging near his face, Acnologia was able to hit Alex and sent him into the cliff-side. "Ouch", Alex mumbled as he pulled himself out of the hole in the rockface. His stealth had been broken and was now staring into the only remaining eye of the massive dragon as it glared at him with malice.
"I needed a dragon eye for an experiment I'm doing, and yours are the perfect color so I thought I'd help myself", Alex said with a smirk to the angry dragon. He didn't know what compelled him to try talking with the dragon, but he couldn't help it.
Not willing to humor the insect in front of him, Acnologia slashed at the human. The dragon's claws took out a great portion of the mountain, but Alex had been expecting a retaliation so he was able to dodge, albeit just barely. After the third time of barely dodging the absurd speed of such a large creature, Alex realized he wasn't going to be able to compete with this monster in his base form. He quickly transformed into his full take-over and was finally able to retaliate. After a couple exchanges he felt his size was a little bit of a hindrance so he started combining his demon form with a type of magic he had only used as a prank and in passing. Makarov's 'Gigantification' magic had been copied long ago, but was quite impractical for most situations. Now though, Alex had an opponent he could finally test the magic on.
When Alex and the dragon were finally at the same eye level, Alex couldn't help but crack his knuckles menacingly. He had never been one of those battle maniacs that sought out a good fight over all things, but he couldn't lie to himself about the excitement of fighting an opponent as storied as Acnologia. The Dragon himself had stopped attacking Alex the moment he started concentrating his magic, letting his full 'giant demon form' stabilize.
"What is your name, Demon?" the dark dragon asked in a deep voice.
Alex hadn't expected the dragon to talk to him, as Acnologia wasn't known for idle conversation. Deciding to humor him, Alex spoke in a deep Voice "I am the Demon, Stormrage", he introduced himself.
"I am the Dragon King, Acnologia! Give me a good fight, Demon!" Acnologia roared in what seemed like excitement before he charged at Alex.
Each clash from the two titans had a catastrophic effect on the surrounding landscape. They matched blow for blow and magic for magic. The devastation in their wake was literally changing the countryside, mountains were being destroyed and rivers were being re-routed with their passing. They fought in what seemed like a stalemate for almost twenty minutes, crossing hundreds of kilometers in both the sky and on land. At one point, Acnologia started laughing at any time they had a small reprieve. He seemed to be enjoying the fight a lot. Even Alex seemed to be enjoying himself.
Alex snapped out of his battle haze after a particularly hard hit from the rampaging dragon. A quick glance around where their fight had been heading and Alex instantly knew they were heading towards one of the major cities within the Alvarez empire. While it wasn't the capital, he still couldn't allow for that many people to get caught up in this mess. Knowing he couldn't beat the dragon through regular means, he sighed as he knew the fight would have to end.
"You are a worthy opponent, Dragon King, but I'm afraid this ends now!" Alex said in his booming demonic voice. Acnologia responded with a deep sinister chuckle and both combatants started sucking in massive quantities of air. Alex knew both of their breath attacks hitting each other would just cause a massive explosion of energy and would stop before either hit its target, so he changed his breath attack into a piercing attack that would force its way through the other attack before striking the dragon. Unfortunately this would leave Acnologia's attack largely unaffected and he would also be hit. Thankfully he had his anti-magic shield, he had enough practice putting the shield up that he figured he could get it up in time. This was all a pretty big gamble though, unfortunately, due to the nature of the shield itself, he couldn't equip it before casting his magic.
The two breath attacks passed each other with little resistance and slammed into their respective targets. Alex had not been fast enough with his anti-magic shield and took the full brunt of Acnologia's breath attack. Thankfully it was only magic and wouldn't actually be fatal for him, it did shatter his gigantification spell though, returning him to his regular demon size. Panting heavily and in a great amount of pain, Alex tried surveying his surroundings. The heat waves and burning forests made it hard to see anything. He could hear the clearly pained howls though and knew the general direction the heat waves were coming from. Flying high enough to get over the massive columns of smoke, Alex finally caught sight of the massive pillar of green flames. The Fel-Fire had expertly latched onto Acnologia's immense magic power and was currently devouring it all along with his life-force. His wings were already gone and he was slowly transforming back into his human form as a desperate attempt to quell the raging flames. Unfortunately for him, the flames had latched onto his life-force. No matter what he did now, it was impossible for him to quell the flames until his life-force ran out, at which point he would die.
The inhuman roars of pain stopped when he was completely returned to his human form, Acnologia actually stopped making noise all together and if Alex couldn't see the man with his own eyes, he would think he had already died. Acnologia was currently watching the flames with grim acceptance before trying to devour the flames. Alex couldn't tell from his position if the ancient being was trying to end his suffering, or claim the flames but in the end it didn't matter. With direct access to his vital organs, the flames claimed the life of Acnologia mere seconds after he took them into his body.
The giant pillar of green flames burned in the crater of molten magma and scorched earth it had created, for an impossibly long five hours. Alex had stayed to watch it burn the entire time and he wasn't the only one. His calamitous fight with Acnologia had drawn the attention of many brave or foolish people that had come to see the destruction. They all gathered as close to the raging flames as they could get without dying from the intense heat, though Alex ignored them all. The moment he had sensed the first one's approach, he had entered stealth. The last thing he wanted to do in his current state was get into another fight. Thankfully, the wizards that showed up had done what they could to put out and contain the forest fires.
When the last of the green flames disappeared, Alex had regained enough of his magic that he no longer felt like passing out. His physical body had also mostly recovered as well. With a final glance to the smoldering pit of rapidly cooling magma, Alex made his way to the group of wizards. He had recognized the aged form of August amongst the group and decided he should leave the old man a message before he left.
"That was the last this world will know of the Dragon King, Acnologia. I apologize for changing the landscape of your country, but it couldn't be helped. Let your father know, if he wishes for his curse to be removed, he need only seek me out in Ishgar. I have already removed your mothers curse. Take care old-timer", Alex said via telepathy. He cut the connection before August could reply and headed towards his nearest teleport pad with as much speed as his still tired body would allow.
Hopefully I did the ancient Dragon atleast a little bit of justice.
Enjoy.