At eight years old, Kael Gremory was a mystery, a menace, and a migraine—depending on who you asked.
He had fully mastered the core techniques of Gojo Satoru: the Infinity, Reversal: Red, his own simple domain, and of course, that unsettling ability to float like a smug ghost in a magical storm.
But what made Kael truly dangerous wasn't his power.
It was that he knew he was powerful—and he was getting bored.
Formal dinners were the worst.
Kael sat in his assigned seat, slightly above it actually, levitating just enough to be disrespectful without being reprimanded. A cup of cursed tea hovered in one hand, steam forming vague insults if anyone stared too long.
To his right, a noble from House Glasya was explaining—again—why devils with "ancient bloodlines" were superior to new ones.
To his left, a noble girl tried to flirt by complimenting his "mysterious aura."
Kael stared straight ahead and whispered into his tea cup:
"System, any suggestions for how to survive the next hour?"
"I suggest vanishing dramatically. Or feigning madness. Want to flip a coin?"
Kael grinned. "Let's try both."
With zero warning, Kael disappeared.
No flash. No spell chant. Not even a magical ripple.
One second he was there, the next—gone.
In his place hovered a card that read:
"Emotionally unavailable. Try again next century."
The nobles panicked. The staff sighed. Venelana, watching from afar, smirked behind her wine glass.
Across the estate, Rias Gremory, now three years old and aggressively attached to her brothers, stormed down the hall in toddler rage.
"Nii-san! Nii-san!" she cried, alternating between Kael's name and Sirzechs' depending on who hadn't picked her up that day.
She burst into Kael's private training chamber just in time to see him rotating midair, cursed threads weaving around his hands in perfect silence.
"NI—"
Kael raised a hand without looking. A thin thread of cursed energy flicked under her feet.
She gently floated backward into a waiting beanbag.
"I love you," she mumbled, mildly stunned.
"I know," Kael replied without missing a beat.
Later that day, Kael left a subtle prank waiting for Sirzechs at the teleportation gate.
The moment Sirzechs stepped through, his boots swapped polarity mid-phase, dropping him headfirst into the koi pond.
Kael strolled past, sipping from a mug labeled "Sibling Rivalry Is Self-Care."
Sirzechs, drenched and still laughing, gave chase.
He didn't catch him.
By evening, Kael stood on the estate roof, arms folded, floating a foot off the tiles, his blindfold hiding a smirk that had been there since breakfast.
"Another quiet day," the gacha system said, amused.
"You sure you don't want a new item? Could roll something spicy."
"No need," Kael murmured.
"But I have a cursed umbrella that screams when opened."
"…Tempting. Save it."
"You're evolving."
Kael tilted his head toward the stars. "No. I'm thriving."
Sirzechs Gremory was not known for scheming.
He was diplomatic. Kind. Regal.
But today?
Today he was a man on a mission.
Because Kael—his mysterious, sarcastic, teleport-happy little brother—was avoiding everything.
Nobles. Etiquette. Responsibility.
And worst of all?
Rias.
At three years old, she had become hopelessly attached to both her older brothers.
With Sirzechs, she was cuddly and demanding.
With Kael, she was dramatic and possessive.
And lately, she cried every single time Kael vanished mid-sentence.
Sirzechs had finally had enough.
So he assembled a plan.
A peaceful family lunch.
A magically insulated dining room.
Friendly conversation.
No traps visible.
Everything about it screamed trap.
He even drafted the invite himself:
"Dearest Kael,
Just lunch. No nobles. Just family. Casual."
He sealed it with a faint suppression glyph—subtle enough to go unnoticed.
Or so he thought.
Kael opened the letter.
He didn't even read past "Just lunch."
He turned to the gacha system. "They're plotting."
"Obviously. Want to roll something explosive?"
"No. I'm going."
"Voluntarily?"
"Oh, I want to see what they think they can pull off."
The appointed day arrived.
Kael teleported into the hallway just outside the dining room—hovering six inches above the ground, cup of cursed tea floating beside him, blindfold perfectly in place.
The door opened.
Inside: Venelana. Grayfia. Sirzechs. Rias.
All smiling.
Rias squealed. "Nii-san!!" and immediately leapt from her chair.
Kael raised a finger.
Gravity rotated. She floated gently into a beanbag behind her.
Sirzechs winced. Venelana covered her mouth to hide the laugh. Grayfia did not bother.
Kael entered slowly, casually rotating midair before landing upside-down in a chair.
"I sensed a trap," he said flatly.
Sirzechs smiled too sweetly. "Don't be ridiculous."
Kael leaned back in the air.
"I was born ridiculous."
Lunch began with polite chatter.
Rias clung to a Kael plush. Sirzechs sipped wine. Kael didn't touch the food.
He was waiting.
Then it happened.
Sirzechs set down his glass. The smile faded just enough.
"So… what exactly is your power, Kael?"
Kael paused.
Then turned his head slightly. "Which one?"
"You know what I mean."
"Oh, the mysterious energy no one else can sense? The one I use to vanish midair, bend space, and make enchanted teapots scream in philosophy?"
Sirzechs narrowed his eyes. "Yes. That one."
Kael sipped his tea.
"Classified."
"You're eight."
"Exactly. I'm a minor. Can't legally self-snitch."
Sirzechs fired a suppressive bind beneath the table.
Kael didn't move.
He simply vanished—teleporting mid-laugh—reappearing behind Grayfia and dropping a small card into her hand:
"You tried. 2/10 for effort. – K.G."
Sirzechs groaned. Rias screamed, "Nii-san's the best!" and clapped.
Venelana laughed so hard she nearly choked.
Grayfia deadpanned, "We should've called Serafall."
Kael's voice echoed from the hallway.
"You will. And I'll be ready."
When Serafall Leviathan heard that Sirzechs and Grayfia couldn't pin down Kael…
She appeared at the Gremory estate with the dramatic force of a magical tsunami.
Sparkles. Wind. Magical girl theme music.
It was, in Kael's words:
"A war crime against subtlety."
She landed in a pose so aggressive it nearly cracked the tile. "Levia-tan has arrived to purge the underworld of mystery!"
Kael, hovering upside down in the hallway, tilted his head.
"Oh look," he said. "A walking migraine."
Sirzechs strolled in behind her, a little too casually.
"You really called her," Kael said flatly.
"She insisted," Sirzechs replied, clearly enjoying himself.
Serafall spun in a circle, glitter trailing behind her. "I'm here for justice. And cake. But mostly justice!"
The plan was outrageous.
Step 1: Fake tea party.
Step 2: Magical suppression field from Sirzechs.
Step 3: Custom binding seals by Ajuka.
Step 4: Serafall in a closet.
Step 5: Interrogate Kael until he cracked.
Kael stared at the table, reading the plan out loud.
"…Did you seriously write 'Activate trap, lol' in glitter pen?"
Serafall winked. "It tested well with Sona."
"That explains her permanent scowl."
The trap was set that evening.
Kael entered the "totally casual" tea room, already hovering two inches above the ground.
Venelana wasn't present. That was his first warning.
The room was too neat. Too symmetrical.
He sipped from the cursed teacup placed before him, blindfold as unbothered as ever.
Rias sat at the end of the table humming happily and cradling her "Nii-san" plush. That was his second warning.
Kael casually whispered to his system:
"They're closing in. Suggestions?"
"Option 1: Hollow Purple. Option 2: nonsense."
"Let's roll some nonsense."
The first gacha roll spat out a singing crab plushie.
It screamed sea shanties in Abyssal Latin.
Kael tossed it into the air. The magical field tried to tighten—but the plushie detonated in harmless bubbles.
Sirzechs blinked. "Was that… singing?"
"Probably," Kael said, already summoning again.
Second draw: a giant inflatable rubber duck the size of a carriage.
Kael appeared seated on it, floating slowly around the room.
"Why walk," he declared, "when you can ride in style?"
Grayfia activated the trap. Ajuka's seals lit up.
Kael vanished again.
He reappeared wearing sunglasses he had just drawn from the system.
They whispered, "Cooler than you" in a smug voice.
Serafall burst from the closet, glitter flying. "That's it! You're cornered!"
"Am I?" Kael replied.
Final draw: a smoke bomb labeled "Panic Button".
He activated it.
Nothing exploded.
Instead, a cloud of glittery fog filled the room and smelled like bananas.
When it cleared, Kael was gone.
On the table, in his place, sat a sticky note:
"Better luck next trap. I rate this 4/10. Bonus point for the duck.
– K.G."
Sirzechs groaned into his hands.
Grayfia marked another failed attempt in her record book.
Serafall screamed, "I WAS SO CLOSE!"
Rias clapped. "Nii-san win again!"
Back in his room, Kael floated over his bed, casually sipping cursed cocoa.
"You could've used real power," the system said.
"Too easy."
"So why the duck?"
"…It had a vibe."
Kael had crossed the line.
Not the moral line—he burned that years ago.
Not the magical line—he rewrote that by age six.
The line he crossed?
The patience of everyone in the house.
The failure of the "Serafall Surprise Special" left the Gremory estate in a state of mild chaos and major glitter contamination.
The only one unbothered?
Kael.
He now casually floated from room to room, sipping tea while humming the crab plush's sea shanty as if he hadn't just made a Maou scream into a couch pillow.
Venelana finally declared, "Enough."
They were done playing nice.
Which was unfortunate… because Kael was just getting started.
The "Kael Containment Protocol" officially launched two days later.
All hallways were layered with subtle enchantments.
Teleport seals were embedded in the dining room floor.
Anti-float charms lined the ceiling.
Sirzechs personally requested a silent proximity barrier.
Grayfia baked cookies—but also added trace glyphs to the tray.
Kael appeared midair, upside-down over the kitchen island.
He stared at the cookie tray.
Then at Grayfia.
"Are the cookies poisoned?"
"No."
"Cursed?"
"Not exactly."
He hovered lower. "Then you've finally run out of creativity."
She blinked. "They explode when dunked in milk."
Kael paused. "…Respect."
Rias, meanwhile, continued her quest to physically attach herself to one of her brothers.
She tackled Sirzechs first.
Success.
Then tried Kael.
He teleported behind her mid-sprint.
She spun in circles, growling in frustration. "He's cheating!"
Sirzechs patted her head. "He's training."
"No! He's avoiding me!"
Kael floated by upside-down, sipping cocoa.
"She gets it."
By midweek, Kael had activated twenty-seven teleport jumps in one afternoon.
He'd dodged:
a scrying net,
a magic mirror interrogation,
a fake letter from "future Sona" asking to meet,
and three surprise hugs from Rias.
That last one nearly got him.
The gacha system chimed softly.
"You're exhausting them."
"I know."
"Want to roll something to make it worse?"
Kael considered. Then snapped his fingers.
A cursed rubber chicken appeared.
It screamed every time it touched a floor.
He dropped it in the hallway before teleporting again.
Behind him, a servant screamed.
Then slipped.
Then set off the milk-cookie trap.
Explosion.
By evening, Kael had warped into the garden and created a false version of himself made entirely of cursed fog.
Sirzechs found it drinking tea and giving vague philosophical advice to Rias.
He stared.
The fog-Kael said, "Time is a hallway with no doors, only prank opportunities."
Sirzechs left without speaking.
Kael floated into his room just before midnight, sipping from a new mug labeled:
"Catch Me, Crimson Daddy."
The gacha system laughed for five full minutes.
"You know they're planning something big now, right?"
"I hope so," Kael said, stretching midair. "I'm getting bored again."
Kael had crossed the line.
Not the moral line—he burned that years ago.
Not the magical line—he rewrote that by age six.
The line he crossed?
The patience of everyone in the house.
The failure of the "Serafall Surprise Special" left the Gremory estate in a state of mild chaos and major glitter contamination.
The only one unbothered?
Kael.
He now casually floated from room to room, sipping tea while humming the crab plush's sea shanty as if he hadn't just made a Maou scream into a couch pillow.
Venelana finally declared, "Enough."
They were done playing nice.
Which was unfortunate… because Kael was just getting started.
The "Kael Containment Protocol" officially launched two days later.
All hallways were layered with subtle enchantments.
Teleport seals were embedded in the dining room floor.
Anti-float charms lined the ceiling.
Sirzechs personally requested a silent proximity barrier.
Grayfia baked cookies—but also added trace glyphs to the tray.
Kael appeared midair, upside-down over the kitchen island.
He stared at the cookie tray.
Then at Grayfia.
"Are the cookies poisoned?"
"No."
"Cursed?"
"Not exactly."
He hovered lower. "Then you've finally run out of creativity."
She blinked. "They explode when dunked in milk."
Kael paused. "…Respect."
Rias, meanwhile, continued her quest to physically attach herself to one of her brothers.
She tackled Sirzechs first.
Success.
Then tried Kael.
He teleported behind her mid-sprint.
She spun in circles, growling in frustration. "He's cheating!"
Sirzechs patted her head. "He's training."
"No! He's avoiding me!"
Kael floated by upside-down, sipping cocoa.
"She gets it."
By midweek, Kael had activated twenty-seven teleport jumps in one afternoon.
He'd dodged:
a scrying net,
a magic mirror interrogation,
a fake letter from "future Sona" asking to meet,
and three surprise hugs from Rias.
That last one nearly got him.
The gacha system chimed softly.
"You're exhausting them."
"I know."
"Want to roll something to make it worse?"
Kael considered. Then snapped his fingers.
A cursed rubber chicken appeared.
It screamed every time it touched a floor.
He dropped it in the hallway before teleporting again.
Behind him, a servant screamed.
Then slipped.
Then set off the milk-cookie trap.
Explosion.
By evening, Kael had warped into the garden and created a false version of himself made entirely of cursed fog.
Sirzechs found it drinking tea and giving vague philosophical advice to Rias.
He stared.
The fog-Kael said, "Time is a hallway with no doors, only prank opportunities."
Sirzechs left without speaking.
Kael floated into his room just before midnight, sipping from a new mug labeled:
"Catch Me, Crimson Daddy."
The gacha system laughed for five full minutes.
"You know they're planning something big now, right?"
"I hope so," Kael said, stretching midair. "I'm getting bored again."