Chapter Text
Demon Keys – Sins
Natsu is the brother of Zeref, having both the Dragon Seed and the Demon Seed inside him, it gives him a special power over demons. Some demons respect Natsu as END, becoming his loyal knights. Those who serve Natsu receive his blessing, their books are reforged and turned into keys, being able to summon them like Celestial Spirits.
Chapter 1 Red Keys
Long ago in the distant past, Natsu Dragneel was reborn. Having died at the hands of a dragon his brother couldn’t rest until he revived his precious brother. He was now a demon, housing a demon seed inside him.
Natsu was taken to a dragon and raised by the Fire Dragon King Igneel. He was taught Dragon Slayer Magic, creating a dragon seed inside him. These two powers would have conflicted but Natsu found a way to unite the two creating a unique power all his own.
The final key to this power came from his teacher, a woman. When the dragons gathered to have a meeting, the children raised by dragons were brought together to learn. Their teacher was a Celestial Spirit Wizard, she was able to summon spirits using magical keys. Natsu would remember this.
Time would pass and Zeref would continue to create demons. Demons of the Book of Zeref they would be called. Instead of magic power they had a unique force known as Curse Power drawing on negative emotions and darker desires. Zeref thought that this power might be the way to finally end his own curse.
He chose seven demons to bare the powers of the sins, Wrath, Lust, Pride, Gluttony, Greed, Sloth, and Envy. Zeref knew the time would come where Natsu would go on a long journey away from him, so he crafted a demon to be loyal to END above all others. It was his task to care and protect Natsu.
Monspeet was born with the Trick Curse, he could switch/swap objects with each other, he could do more than two but limited himself to two to trick opponents.
He was ambidextrous, sometimes used a rapier but could fight bare handed or with his power. His hobby was Protecting and taking care of Natsu, the daily routine consisted of getting Natsu ready for the day, sparring and training. He had a charmpoint of being Very muscular, his rippling muscles hidden under his clothing. His special ability was keeping secrets.
Monspeet became Natsu’s confidant, even keeping the secret that Natsu had a crush on Gajeel.
Then came the day, Igneel was gone and Natsu was heart broken. He wasn’t eating, wasn’t sleeping, Monspeet was beside himself. The demon did the only thing he could think of, he gave Natsu his book. “This is me, all of me, everything I am is written here. My life is literally in your hands.”
Dragneel looked from the book to the demon, then back to the book. “If something happens to this, that means you’ll disappear too...just like Igneel…” He began to cry.
‘Ohh shit.’ The hybrid cried for three days, he wouldn’t let go of Monspeet’s book the whole time. Monspeet wanted to tell him the truth, but it was a secret and he couldn’t.
Then Natsu got determined, he began channeling his magic. He truly was his brother’s brother, the wheels of his mind worked and he crafted a new power.
Natsu performed his ritual, using his twin seeds, he mixed magic and curse, crafting a Demonic Key, it was Crimson Red and looked like a Celestial Spirit Key. “Do you trust me?” He looked at Monspeet with a serious look.
“Of course, with my life and everything I am.” Natsu touched the key to the book. There was a flash of light and the grimoire was gone and a symbol appeared on the key. Monspeet vanished from sight, and appeared in a new realm.
It was a subspace crafted by Natsu’s soul, a Beta Heaven so to speak. The place was rather beautiful, it seemed to be endless. There was just one problem, Natsu was gone. “Natsu...Natsu...Natsu...Master!” Monspeet called out in desperation.
“Open Gate of Ashes!”
Monspeet was summoned back. “I did it, I did it!” Natsu bounced up and down.
The demon stared at Natsu in shock and awe. He felt different, he felt not only his curse power grow stronger but something else...he had magic. He was given/taught Fire Magic. Monspeet was able to perform Fire Make Magic, so he could craft and mold fire into different forms. His style was beasts.
If something were to happen to Monspeet, his physical form would only be dispersed, he’d return to Natsu’s subspace and reform. Monspeet was happier then he could admit, he felt truly bound to Natsu.
“I want to find the others, is that possible?” Monspeet nodded.
Natsu joined a guild, so he could train and gain leads on demons. Some demons went with him willingly, others needed a bit of convincing. Thankfully with Monspeet’s training Natsu was a lot stronger, he could even tap into his Etherious form, a demonic form with dragon traits.
Over the years he found Four of the Seven Sins. Meliodas the Sin of Wrath was lost, having spent his life traveling. Over the last 400 years, he’d tried to settle with humans only to watch them grow old and die, while he didn’t. He suffered the pain of loss over and over, eventually becoming a nomad, loneliness was his constant companion.
Meliodas wondered if Zeref knew this was gonna be his fate, thus giving him the Curse Double, where he could make a double of himself. When he met Natsu he fell in love.
Zeldris, the sin of Pride, also fell in love, but he was Tsundere about it. He had been “captured” by Vampires. The vamps didn’t care about Zeldris just wanted his blood to increase their power. He wanted to use his Curse Domination, but the vamps had crafted the Dark Coffin, a magical item that sealed Zeldris’s curse, he was helpless, going cold.
Natsu had taken the job took out the nest and rescued Zeldris. The raven haired demon felt a spark and was taken in by Natsu’s warmth. The Dark Coffin was shattered and the pieces scattered.
Meliodas was happy to have his brother back. Zeldris was equally happy but said nothing, trying to play it cool.
They were able to track down their brother Estarossa the sin of Envy, they weren’t brothers by blood but they had been made by Zeref at around the same time. Zeref wanted to learn about brotherly bonds, he’d lost Natsu at such a young age, only to lose him again.
He tried to use his curse on Natsu, but thanks to the demon seed training Natsu was able to counter it. Estarossa became the victim of his own curse and he became putty in Natsu’s hands.
The Sin of Greed Ban, had built a whole foundation of thieves, the 100 Thieves became a target and Natsu went to handle it. He recognized that Ban was a demon immediately, he could tell by scent.
Ban wasn’t gonna bend a knee easily, so the two fought for a whole week. It was the best fight Ban ever had. “Sweet fuck I...I love you!” He looked at the pink haired man. “I think you stole my heart.”
The bandits and thieves Ban united disbanded, Natsu gave them some mercy as a favor to Ban.
Natsu performed the ritual, having their books absorbed by the keys. They gained magical powers, and became even more fiercely loyal to the hybrid.
The last three demons he obtained, had simply been causing trouble. Gilthunder was tormenting a town, his power disrupting the flow of special water they used to make ale. He was making them pay tribute.
Natsu showed up and Gilthunder did recognize him, but he wasn’t just gonna submit. “If you want me to serve you, you’ll have to best me in…”
Dragneel beat his ass, spanking him, and knocking him around. Gil even tried to transform, gaining Tiger-like traits in his Etherious form. The curse was lifted and Natsu claimed Gilthunder as his own.
Another demon known as Howzer had actually come looking for Natsu, wanting to test his strength against END. He came to town in a massive twister, he could have brought havoc and destruction. The demon had more balls than brains, and Natsu put him in his place.
He thought his wind could snuff out Natsu’s flames, but Natsu was older and more powerful, even against cursed winds. When pushed to it, Howzer transformed, showing off lizard scales. He tried to say he was a dragon, but he was a lizard not a dragon.
After his loss Howzer swore his loyalty to Natsu. He was taken under his wing and gained a rather unique ability. Howzer was designed to have a weakness with women, Zeref may have been going through something when he created Howzer. His magic power allowed him to change women into men.
The last demon was known as Griamore, he had trapped an entire city under his massive barrier. He refused to release anyone unless he was defeated in battle.
His Curse power was tricky, his Barrier Curse was powerful, the defensive power alone could handle Natsu in full Etherious mode. He tried to capture Natsu in spheres, Natsu flying through the air to avoid getting captured. “Zeref made me to be the ultimate shield, a living fortress that will never fall.”
Natsu could have ended this quickly with his Curse Incinerate, the power that made him cancel and counter the effects of a curse. A safety measure Zeref built, so none of his creations could kill his beloved brother. He wanted Natsu to potentially lead his demons against him, but his creations could develop and evolve so he wanted some insurance.
While Natsu could have done that, where was the fun in that. “I hoped to have a full on rumble with you, but seems I’ll have to crush you with full force.” His eyes burn. “Open Gate of Ashes!”
He summoned Monspeet, and the tides turned. “Fire Make Birds!” He constructs flaming birds and let them fill the air.
“What is this?”
“Trick!” In an instant Griamore was pulled from behind his barrier and was swapped with one of the fire birds.
“Ehh?!” Natsu came in swinging hitting him hard. One blow wasn’t enough to settle this.
The fight was on but Griamore had lost his edge, one man may not have been enough to siege his fortress but Natsu wasn’t alone anymore.
Griamore managed to trap Natsu in a sphere and tried to crush him, but Monspeet just activated Trick, and switched Natsu and Griamore. “Damn it!”
Natsu ate some fire birds to recover his energy. “Mmm spicy!”
Griamore tries to end this by transforming. He gained Turtle Traits, but this wasn’t enough. Natsu came out the victor and Griamore bent a knee, swearing to serve Natsu and be his shield.
After that, the leads for other demons seemed to dry up. Natsu didn’t let it him get him down, he instead focusing on training and working with his loyal knights. His skills and abilities reached the point Natsu was recognized for the S-Class Exam.
To be continued...S-Class Trial
Erza, Mira, and Laxus were in charge of testing the applicants this year much to the horror of the applicants and excitement for Natsu. He wanted to challenge Erza or Laxus. The game was a twisted game of Chase, applicants had to find clues to the location of the goal, Erza and Laxus were the “Hunters”. Laxus defeats Cana before setting his sights on Natsu. The hunters had special clues that made finding the goal easier, so it was high risk high reward facing them.
Meliodas – Wrath – Curse Double – Magic Counter
Zeldris – Pride – Curse Domination – Magic Shadow
Estarossa – Envy – Curse Heat – Magic Sunshine
Ban – Greed - Curse Hunt – Magic Snatch
Gilthunder – Gate of the Storm – Curse Thunder – Magic Beast Taming
Howzer – Gate of the Twister – Curse Tornado – Magic Masculine
Griamore – Gate of the Fortress – Curse Barrier – Magic – Size Magic