He who fights with monsters should look to see that he himself does not become a monster. And if you gaze long into an abyss, the abyss also gazes into you."
This phrase is a warning to anyone traveling a path that won't be easy to stray from. If someone were to fight a monster that threatens the very existence of themselves and those around them, they have to be careful not to become the things they have to defeat. Otherwise, a deadly cycle would form that won't be easy to break. Anyone who becomes an abomination will have the abyss swallow them whole, because they blinked, leaving themselves able to fall into its grasp.
But what if the abyss were more... literal?
There was a large void of space, where there was nothing. It was incredibly empty, there was not a single person to see, meet, and interact with. There was nobody. Nobody… except one.
A lone entity lived there, sitting on a throne out of his own design, standing in what little light existed in the plane. The being had their cheek resting on their fist, their elbow standing on one of the armrests of the throne while the other hand laid flatly on the opposite armrest. They bore an indifferent, tired expression on their face, lost in thought.
"I need more recruits for my army." The being said finally.
"It's only a matter of time until I am stuck here forever." The entity growled.
"I won't be trapped in this eternal hell hole ever again!" He shouted in unsaturated anger.
"I was so close to rebuilding my empire, then it was taken from me like it was nothing!" He continued venting, breathing heavily from all the shouting until eventually he calmed himself down.
"I need fresh meat." The entity decided. "People who have the drive to get the job done, but offer new abilities and characteristics." The figure swiped his finger across the air, summoning a giant screen before them.
"Let's see what we have here now."
He began scrolling through the screen, trying to find anything of interest. It wasn't long before he saw something that fit what he was looking for.
"Finally, I found it."
Two pictures were then shown, each showing a different person.
One showed a picture of young man aged 19, with green eyes, an extremely impressive physique and was currently shirtless with only brown pants covering him his name is
"Eren Yeager."
The other showed a salmoned haired boy, who looked to be around the same age as the other, but a bit older. Besides his hair, he has black eyes, wore a white scaly patterned scarf, had a one-sleeved black vest with gold orange lines, white pants, and beige colored sandals. Last but not least, was a red colored symbol on his right shoulder that resembled a creature of some sort.
"Natsu Dragneel."
The figure pressed a button and two character profiles on the individuals along with videos showing their lives and experiences appeared. It showed the date of their birth, their pasts and futures, and their unique abilities.
For Eren, he wears a special device created by his kind that allows him to move in a three-dimensional space equipped with hooks, gas canisters, two metal boxes that acted as sheathes, containing four plug-in blades each, and finally the main housing unit that connects the whole system together.
This unique equipment is known as Omni-Directional Mobility Gear. The purpose of this weapon is to combat creatures known as Titans that are too big to fight against normally. He also had the ability to turn into a Titan, a special one named the "Attack Titan", making him a being called a Titan Shifter, with his form having great strength, endurance, and agility.
It can harden its skin to protect itself and increase its damage as well. Besides being able to transform, this power allows Eren to regenerate virtually any form of damage done to him in both human and titan form, from a small cut to a chopped-off limb.
Natsu on the other hand is a wizard, whose specialty is Fire Dragon Slayer Magic. Following its name, this magic can hurt and even kill a Dragon with special draconic flames. With this power, he is immune to the effects of the element and can even consume it to replenish lost stamina and increase his strength.
He can even go past this limit to consume elements other than his own if he tries hard enough. This brand of magic can also allow wielders to access a form called "Dragon Force", which is the strongest state a dragon slayer can achieve normally, making them just as powerful as a dragon.
But this power has a drawback: when a Dragon Slayer overuses their magic, they become a dragon themselves, but they can change back if skilled enough. This power also has the adverse effect of making the user experience extreme vertigo, and as a result can't ride any form of transportation without getting motion sickness. Other than his magic, Natsu is a skilled fighter with high levels of strength, endurance, speed, and durability.
The entity looked over their character profiles.
"Interesting. They appear to be two sides of the same coin" said the figure.
"However, one has less chances to reach their full potential than the other."
The being turned his attention over to Eren's profile and began to look into the videos showcasing him and his powers and skills.
"His titan abilities are impressive, but it's too bad he doesn't get a chance to use that fancy equipment his kind has made, even then it has its limits and is incredibly fragile." said the entity.
The video showed all the moments when he shifted into a Titan and the few instances where he used the ODM gear, including the time where he took down an enemy Titan Shifter with no problems.
"He is an extremely driven individual. Even though his powers are restricted in a sense, that doesn't stop him from reaching his goals. I can see what he is capable of because of that, especially towards the end of his life"
The entity then looks over to another video to see Eren is his titan form, but not his usual one. The form is 250 ft tall, high enough to reach the sky. This form has an extremely long and gigantic rib cage with spikes protruding from the spine. At the front, the main part of the body has a smaller spine and rib cage hanging from it, with the arms being connected to the large ribs by a thin line of hardened skin, taking an appearance similar to a puppet hanging from a string. Lastly, his new titan body has a longer neck and sports a different facial structure than the original.
"There aren't that many that can rival him in pure determination and willpower, except for one."
He then looked over at Natsu's profile.
"On the other hand, this individual has had similar experiences, but he has gotten more opportunities to increase his abilities and grow."
The videos on his profile show his powers and all the times he's gotten stronger, especially through the use of consuming elements, both fire and others such as lightning and a crystal full of different elemental magic. It was because of his power to eat elements that he was able to access powerful modes such as Dragon Force and a Dual-Elemental Mode that can allow him to wield two elements at once and use both to their fullest capabilities.
"His ability around fire is astounding, but I wonder how far he can reach his true power with his magic, especially since he can access the powers of a dragon and the ability to harness other powers besides his signature flames."
The entity brings up some videos showing all the times Natsu was in his Dragon Force state, as well as how he ended up in those forms, showing him consuming Ethernano: the source of magic in his world, a very powerful Fire Magic spell, achieving dragon force on his own, and finally when he devoured a legendary Fire Dragon's flames.
Other videos involved him fighting in his Lighting Flame Dragon Mode, a form that granted him both control over fire and lightning, combining both powers to create devastating attacks and harnessing the aspects of flames and electricity to the max.
The figure then turned over and looked at both profiles at the same time, thinking about something while watching the two boys in action in their respective footage.
"They may look different, but their personalities, their history, choices, the people they've interacted with, even their powers, while not exactly similar, are one in the same." the figure concluded.
The creature pulled a picture of a field containing rocky lands, mountains and cliffs, and finally forests covering almost the entire biome.
"I want to see what happens if they were to do battle, it may seem obvious who the winner is, but there is more than meets the eye, especially with these two. This will also allow me to the full extent of their capabilities and see if they are fit to be generals for my army."
"They are the most determined individuals I have ever seen: let's see what they got." The creature said while setting up the battlefield that the picture was showing.
"However to even out the playing field lets increase Eren's physical capabilities to the Pinnacle Peak Human level it's not like he isn't already close to it so it should be fine to make it official. Yah that seems to be fair."
"Now everything is ready."
"This will be a fight that will be remembered for a millennia."