Teenage Mutant Mystic DEMONS AU
[ Subject SN-21. The Ghost. The Wraith. Baby Sibling ]
Agender. Listen, it's hard for him to perceive gender when it's a human social construct, and he was raised out of human society.
Ghost Mutant: half-mortal, half ghost. The product and sole survivor of the successful human experiment, "Project Ghost."
The youngest among the four kids, and also the shortest. The Maou trio sometimes refer to him as "Baby Sibling," even when he's just a year or two younger than them.
Sena was taken from his parents when he was but an infant. He grew up in the Deimon facility, and was basically raised by the scientists who experimented on him.
Because of this, Sena never truly had a name before Doburoku adopted him and the others. The scientists only ever called him, "Subject SN-21."
It was the Maou trio who started suggesting names for Sena, after their adoption.
Hiruma kept suggesting ridiculous names like "Ghost" or "Wraith" or "Chibi."
Kurita and Musashi, however, were the ones who successfully coined the name, "Sena," as the boy was still attached to his subject name, SN-21.
Hiruma (they/them), feeling petulant that no one picked their suggestions, started calling Sena the nicknames thay they came up with anyway. When Hiruma wants to intimidate the opponent, they call Sena either "Ghost" or "Wraith."
But usually, Hiruma just calls him, "Chibi." It's Hiruma's special nickname for him, because Sena is the youngest among them. Sometimes, Hiruma likes playing around with the letters of Sena's name, and making him new nicknames.
Hiruma has called Sena: "Lil Nas X," because it has the letters S-N-A. They've called Sena other nicknames like: Onsen (hot springs), Senichi, Five Sen (an ancient banknote), Senshi (soldier), Senzo, Kaisen (fight/battle/war), Senmatsu, and even Sen no Sen (to attack your opponent before they initiate the attack they've decided on.) Hiruma thinks it's funny, and Sena doesn't really mind the nicknames.
Unlike the Maou trio, Sena never actually got to experience the ups and downs of human society.
So the Maou trio and Doburoku take him to the closest city from time to time, just to show Sena what human society looks like. They make sure he tries even the most mundane of things to give him the full experience.
The first time Sena tried pizza, his eyes lit up like stars at the taste. The scientists only ever gave him bland foods at the Deimon facility (feeding hundreds of trafficked children was expensive). Because of that, Doburoku and the Maou trio make it a contest to feed Sena different types of pizza, hoping to find his favorite flavor.
Sena doesn't have a favorite flavor of pizza, though it has come to be his favorite food. And pizza has only become his favorite food because it's party size. He loves it because he can share it with others, and because it's delicious!
Sena is often forgetful because of his trauma. He doesn't remember most of his childhood (his brain is trying to protect him to cope) but he does remember the times when the experimentation hurt the most. And sometimes, he wakes up screaming, or wakes up in the midst of a panic attack.
Because of this, the Maou trio do what Dokuroku calls a "Demon Pile." The Maou trio all sort of puppy pile onto Sena, engulfing him in comfort and safety. Doburoku makes hot chocolate of everyone, and plays some comedy movies on TV.
When Sena is toeing the line between wakefulness and sleep, that is when he is the most honest. He whispers, "Love you guys," right before he falls asleep. The Maou trio, with their enhanced hearing, will always hear it. It never fails to make their hearts squeeze.
Because Sena's the youngest, he also has the "baby sibling privileges," so to speak. (Not that he knew what that truly is, because he was raised in a metaphorical media & culture vacuum.) Sena doesn't often ask for things, so when he does, the others would practically serve him the moon on a silver platter.
Hiruma would burn down civilizations for him. Musashi, the mechanic and engineer of the family, would practically build Sena the Tower of Babel, if he asked. Kurita would crush armies for him.
Sena returns this affection with his whole being. Not really knowing what "morals" are, he would do anything for the Maou trio as well.
Sena, without his own knowledge, sometimes becomes the most brutal of his siblings when it comes to battles. More so when one of his siblings get injured, which is the one thing that angers him.
Sena rarely gets angry, even when strangers push him around. This is an effect of the scientists dehumanizing him during his childhood. The constant abuse made him think it was normal to suffer.
To combat this way of thinking, the Maou trio and Doburoku have to drill it into Sena's brain again and again: "You do not deserve to feel suffering and pain. You must not endure abuse. You must fight back, and fight for yourself."
Out of all of them, Sena has a bad habit of self-sacrifice. Having a low to non-existent sense of self-worth, he would endure even the greatest of pain for his siblings. This makes him the most predictable in battle, because when he sees one of his family about to fall into mortal danger, Sena always uses his powers to switch places with them to take the blow instead.
This is a pain in the ass, as the Maou trio care for him goddamn it, and don't want him getting hurt just to protect them. Hiruma and Musashi, being the inventors and fixers within the family, try to come up with inventions and ways to stop Sena mid-act. Kurita (she/her), as the tank, trains herself to be faster and stronger, so that she can stop Sena, and so that she can take harsher blows, to protect her siblings.
Sena started loving videogames an anime, ever since Doburoku started bringing home some games and anime DVDs from the city.
The knowledge from anime and videogames proves beneficial for the kids. Sena shows the others things he thinks they might like, from the anime and games.
He shows them cool moves he thinks they can execute as a team or individually. Battle formations, combo moves, and even sneak attacks.
As the strategist of the family, Hiruma (they/them) loves it when Sena shows them a new move he saw in a game or anime. And as the gunsmith and weaponsmith of the family, Hiruma always pay attention when Sena shows them a weapon that he thinks Hiruma would like. Rocket launchers, flamethrowers, guns, artillery, and even drones—whenever Sena shows them these, Hiruma would stop whatever they're doing just to watch.
Musashi always pays attention whenever Sena shows him a cool invention he saw from the futuristic and steampunk anime and games. Since Sena knows Musashi wants to improve their standard of living to the best of their abilities, he never fails to send screenshots and recordings whenever he sees Musashi interested in a specific fictional concept he found.
Sena sends Kurita (she/her) food from his anime and games, because he knows Kurita loves the challenge of creating a recipe, merely from a dish's final product.
Once Doburoku introduces Sena to Youtube, it becomes his primary source of information. That's where he starts actually learning about human society, and how humans act.
The family often learn Youtube terms and memes from Sena. Sometimes, Sena seems to be speaking another language entirely when he starts spouting videogame terms, or things like, "Skill issue," or "For real for real," or "L + Ratio." He's often the one to teach them what these terms mean, and Hiruma (they/them) always listens so that they can add to their vocabulary to roast their opponents better.
Because Sena was raised alongside Hiruma, this version of Sena is more playful, more willing to play pranks on his brothers. He is also less reserved and more open, as he trusts his siblings with everything.
Sena is also the most honest of his siblings. He has a hard time lying, because he has no practice. This is exactly why Doburoku, their adoptive parent, tends to always ask Sena first when he and his siblings get in trouble. As such, scenes like this one are common:
DOBUROKU: Sena, what's the matter?
SENA: [sweating bullets, eyes roaming everywhere in panic] I... Uh... We...
HIRUMA: [under his breath] Don't you rat us out, fucking chibi.
DOBUROKU: [raising an eyebrow] Well, kid?
SENA: I—uh—guh... The truth is....
HIRUMA: [raising a frying pan] Snitches get stitches.
KURITA: [grabs onto Hiruma, restraining them.] Hiruma, NO!!!
HIRUMA: [trying to wriggle free] Hiruma, YES!!!
MUSASHI: [softly bonks Hiruma's head] Stand down, idiot.
EVERYONE: [Dead silence.]
HIRUMA: [slowly lowers his frying pan]
DOBUROKU: Listen, if you're gonna lie, you have to try harder. But I commend your efforts, kid. [The smell of fart reaches his nose.] Oh, you weren't joking.
Sena has the cleanest room among his siblings. It amazes the others to no end.
Sena is actually extremely interested in farming, and in plants overall. Being raised in the confines of the Deimon facility, they only know white tiled floors and grey walls. They've only ever seen plants in their food. So among his siblings, he is the most ecstatic to join Doburoku in farming their own food.
Among the kids, Sena has had supernatural abilities the longest. Being the sole survivor of Project Ghost means he had ample time to get used to his abilities long before the Deimon facility exploded.
The scientists tested the fuck outta him, so even as child, he's familiar and quite in-tune with his ghost abilities.
Sena can see spirits (as he is some sort of hybrid ghost as well), and can interact with them.
His default is that he floats a few inches off the ground. To look normal, he has to concentrate on making his feet touch the floor.
He has the ability to pass through people and objects, and if he so pleases, injure those he passes through.
This ability also proves useful, as Sena technically breaks down his molecules into energy particles colored black and blue. He then reconstructs his body in a burst of light.
This is actually why Sena's main weapons are knives. Despite being easily terrified, Sena's Ghost Abilities are better for close combat.
Sena can also turn invisible. His favorite, non-lethal strategy is to disappear, and tie up his enemies while they can't see him. In this state, time moves slower for Sena, so he appears to be a dozen times faster than normal.
This ability proves useful, as Sena is an unstoppable force in this state. The probability of enemies interrupting this move is extremely low, as Sena becomes physically untouchable.
When Sena wants to do damage, this is what it will look like in Sena's POV, due to the light difference in time dilation:
To the outside eye, he looks like he's teleporting, but he truly is not. He just deconstructs his molecules, zooms towards a direction, and the reforms his body. He does, however, develop teleportation as a mystic power.
Sena can also disappear in a cloud of smoke. This usually happens when he's too terrified. Disappearing is a flight defense mechanism, reminiscent of turtles retreating into their shells.
However, when Sena dissipates into a cloud of smoke, he leaves his skull behind. It drops to the ground, unhindered by the confines of his semi-mortal form. This skull contains the essense of his soul, so the Maou trio take care of it when Sena dematerializes.
When Sena disappears while the four are fleeing from a terrifying enemy, the Maou trio scramble to snatch his skull into their hands, and then run.
Sena's mystic power is the ability to teleport using portals and conduits. At first, Sena was extremely disappointed to find out about this. To the untrained eye, his ghost abilities already looked quite similar to teleportation.
But then, Sena found out that he could open portals that led to far-off places as well. This, the while family thought to be extremely convenient, as they could just portal from place to place.
He can also use portals in battle. He can launch himself and his brothers into portals, as a sneak attack. Like so:
He can also use objects as conduits, to teleport from one place to another. He litters his mystic energy onto objects or in the air, and then uses those as a sort of landing pad to reappear where he left his mystic energy. In the midst of combat, he mostly uses his knives, like this:
With Sena's ghost abilities and mystic powers, it is a fact that he is the fastest among them. So as a failsafe, the Maou trio allow him to scatter some of his mystic energy onto them, and onto their gear. This ensures that when one of the trio are in imminent danger, at least Sena can reach them.
Sena's mystic powers are a manifestation of his wish to travel all around the world, and his wish to protect his siblings. Sena knows he is far from Kurita's and Musashi's strength, and even farther from Hiruma's intelligence. So Sena settles for his speed; the one quality he can be relied on to possess.
After Sena stabilized his portalling mystic powers, he and the others started going to cities more often.
Learning from the ultimate prankmaster Hiruma, Sena also sometimes pranks the others. It's all ultimately harmless; sometimes, Sena would portal them somewhere a foot above the ground, so the others stumble a little when they fall.
Sometimes, Sena would portal his brothers to bump into each other when he's feeling playful.
NOTE: This AU is subject to constant changes, as it is still currently under construction.
Feel free to write or make art of this AU. But please credit me, and send me the link to what you've made! I'd love to see it!!!
This AU was based on Rise of the Teenage Mutant Ninja Turtles (ROTTMNT), and further inspired by RWBY, The Locked Tomb, Honkai: Star Rail, Fullmetal Alchemist, Solo Levelling, and Genshin Impact.
