Kuroka slunk quietly through the Dantalion estate.

She was taking a gamble here, being in the home of one of the prominent Pillar families while the Naberius agents were hunting her, but she needed to get out of the Underworld as soon as possible. The public transit stations would be heavily monitored, and she wasn't strong enough to teleport between realms.

Yet, Kuroka told herself.

She wasn't strong enough yet.

One day, she would be.

She'd be strong enough to come back here, rescue Shirone, and leave.

She'd be so strong that they'd be able to live together and wouldn't have to worry about starving or being victims ever again.

The thought of her sister made Kuroka's heart ache, but she swallowed the tears.

She could curl up and cry when she was safe. All she could do for now was hope that Shirone would make it. Kuroka had wanted to take her with her, but she hadn't been strong enough to deal with all the Naberius devils and keep Shirone safe at the same time.

Kuroka would have to content herself with killing her King and destroying the research on Senjutsu, even if it meant she couldn't prove her innocence.

A small price to pay if it meant protecting Shirone.

Nobody should have too much interest in Shirone now. By law, her sister could not be held accountable for Kuroka's crime.

The new Stray Devil tried to ignore the whisper in her mind that most Pillar families ignored the law when it pleased them.

She failed.

Still, the failings of the devil government were a boon at this moment. Pillar families were allowed to maintain teleportation circles to the human world that were entirely private. The Dantalion house was no different, despite being on the weaker end of the remaining 32 Pillar families.

Kuroka knew little about the family, just that their clan trait was relatively weak in a direct fight, and their territory was somewhere in Africa. It was enough to know that they weren't a big house, by noble standards at least, and kept to themselves.

Which meant less guards and scrutiny as she snuck through the halls, as silent as a cat in the night.

In and out with nobody the wiser, that was the goal.

Kuroka was exerting her full effort, whether with her Youjutsu, magic, or Senjutsu, to remain invisible and undetected as she searched the unnecessarily large manor for their teleportation room.

Eventually, she found something by following the life signs she detected using her Senjutsu.

Not the teleportation room.

"-ver one human?" An apathetic voice asked.

Kuroka snuck closer, hoping to either overhear what they were saying or discover where they would avoid the speakers. One was on the stronger end of High Class, while the other was only Mid at best, so Kuroka could take them if it came to a fight.

...Maybe.

It had been a few days without food or sleep, and Kuroka wasn't at her peak state either.

"A human that managed to defeat Griselda Quarta," a second voice answered defensively. "I've been keeping track of him for a few years now. He's talented, brutal, smart, and follows orders. He'll make a good Pawn."

"He is a human boy with no magic, skills, or Sacred Gear," the first man snorted derisively. "You should have captured that woman instead of missing such an opportunity. Or her Holy Sword. Both would make good trophies. Instead, you took a child. If you fill your Peerage with weaklings we will never rise in rank. Kill him and find someone else."

"I will if he does not meet my expectations, but once Whisper takes control, I'll reincarnate him. I do not wish to end up like Naberius. You can test him then, Father. I believe you will be pleasantly surprised."

"Very well. It won't be too late to take your Pawn back then. He better be worth all the effort."

"If nothing else," the younger man said with some humour. "Someone called the 'Child of Evil' is destined to be a devil."

"You got your love of dramatic irony from your mother."

"That is not how she tells it. She told me yesterday that you-"

The two devils turned a corner, and Kuroka stopped listening.

The Black Cat's mind raced a mile a minute.

That was probably Lord Dantalion and his heir. Based on their conversation, they had recently returned from the human world with a prospective new devil in tow.

Now, Kuroka was faced with a dilemma.

Whoever they captured might know where the teleportation circle was if they weren't unconscious when brought to the Underworld.

But sneaking around with someone else would be infinitely more difficult than doing it alone.

There was also no guarantee they would help Kuroka.

She had seen how the test subjects would do anything if they thought it would save them from being the next one under the knife. They might yell and try to turn her in if it meant going free.

In the end, Kuroka decided it was worth the look if only to find out who had defeated the legendary Griselda Quarta.

Curiosity led the Black Cat down halls and peeking into rooms.

Senjutsu allowed her to feel the life force of everyone in the mansion, but even though Dantalion was small for a Pillar family, that still meant their manor was massive and filled with hundreds of servants. Kuroka had no idea who she was looking for.

Following the rule of thumb, because most devils were cliche like that, Kuroka searched for a basement dungeon.

And, after only a half hour, she found a passage barred with a thick door and two guards flanking it.

It definitely looked like the type of place that led to a dungeon and maybe a teleportation room.

Invisibly, and with her presence as suppressed as possible, Kuroka wove an illusion over the guards so they didn't notice her paw one of their keys and slip through the door.

Because devils were creatures of opulence, even this part of the mansion was needlessly vast and sprawling.

It was only after descending two flights of stairs, passing through four wine cellars, and carefully avoiding a room that smelled so thickly of sex that Kuroka was sure it was a different kind of dungeon that the Stray Devil found the actual prison cells.

Only one was occupied.

A young boy, only about nine or ten, hung from the wall by chains wrapped around his arms and legs.

It was clear the bonds were designed for full-grown men and women, so they painfully hung his arms over his head and pulled his legs down. He was bruised and bloody, though without any severe wounds that Kuroka could see.

Magic swirled around him. Not his own but that of the younger Dantalion she had seen upstairs. Sounds and sigils flashed intermittently in the air as if whispering words that were just out of reach.

Kuroka didn't know if this was the Dantalion bloodline ability or a really advanced spell, but it was perhaps the most complete hypnosis spell she had ever witnessed. Leave someone in there long enough, especially a human without a devil's ability to resist magic, and eventually, they'd be reduced to a mindless servant.

All this Kuroka noted with a glance, prodigal as she was with magic.

It was for the best because her whole focus was on the boy.

The boy staring at her.

Grey eyes stared right at her from under filthy brown hair matted with blood and dirt.

Kuroka took a step back, fearful that she had been caught.

Then she realized she must be imagining things. She was still invisible and had her Ki suppressed. Only a supremely talented mage or sage would be able to sense her.

Then the boy spoke in a voice that was flat and empty of all emotions.

"Black Cat Kuroka."

This time, Kuroka did flinch.

"I want to make a deal with you," the boy continued, still staring at her.

Kuroka dropped her invisibility, though she kept her presence suppressed just in case anyone in the manor above had a sensing ability.

"A deal, nyaa," she said, sashaying her way closer to the cell bars. She was disconcerted but wouldn't allow this boy, whoever he was, to see that. She wasn't really dressed to impress, being dirty and not having bathed in days, but he was too young to have that sort of worry. "With you? What sort of deal? And how did you know I was here?"

If there was a flaw in her stealth, she needed to know about it right away.

"A deal of mutual benefit. You train me in Senjutsu, follow my orders, and act as my right-hand woman."

The way the boy spoke, so empty and emotionless, sent shivers down Kuroka's back.

She didn't let it show, though. She couldn't show weakness.

Kuroka had learned that the hard way.

"Ara? You want Onee-sama to be your lap-kitty? I don't wannyaa. I killed the last man to try."

"In return, I promise to give you the chance to reunite with Shirone."

Claws pressed into the child's throat, drawing a trickle of blood as feline yellow glared into impassive grey.

"Who are you," Kuroka hissed angrily.

She was tired. She was hungry. She was afraid.

Kuroka was at the end of her rope and one wrong move from this boy could very well send her over the edge.

"My name is Eren Yeager," the boy said impassively. "I know about the experiments. I know you killed your King to save your sister. I know how to clear your name. I know how to give you a chance to make up with her."

"How do you know all this," Kuroka demanded, skin tearing further under her claws. "Are you with the Naberius? Have you been spying on me?"

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"I know this because you tell me it," Eren answered. "I know because I can see the future."

"No Sacred Gear can see the future," Kuroka denied. "Not even the Agares can see the future."

"It's not magic. It's not a Sacred Gear. Just me. You don't have to believe me now. You will later."

"I'd be more likely to believe you if you didn't end up in a lordling's dungeon," Kuroka taunted, trying to draw the boy's anger. Maybe he'd let the truth slip. There was no way he could see the future. "What's wrong, boyo? Didn't see this coming, nyaa?"

"It was the quickest way to meet you after you killed your King," Eren answered easily. "I can escape any time I want."

Kuroka lept backward as Eren's open wounds crackled with small bursts of electricity.

A silvery-white material flowed from Eren's back and sharpened into a scythe-like blade.

Kuroka readied herself to teleport through the bars again, but she needn't have bothered.

She was not the target.

In one swift motion, the blade severed the child's arms and legs.

Eren fell from the wall, landing on the ground with a 'SPLORT' of blood from his severed limbs.

Kuroka watched it all with horrified disgust.

What sort of mad child had she found?

Then she noticed something.

Steam wafted from the wounds as the white substance lifted the boy from the ground and propped him against the wall so he could look at Kuroka once more.

His wounds... They were healing.

Quickly.

Incredibly quickly. Far faster than any regeneration she had ever heard of outside of gods.

It would be only a few hours before the boy regained fully functional arms and legs.

That was insane. Even the best healing in the world could not regenerate limbs. Healing miracles were one reason the God of the Bible gained such a following.

Eren didn't seem to care about what he had just done to himself.

Like he was so used to pain that he didn't even feel it.

"Give me ten years," Eren said in that emotionless voice. "I will give you a chance to reunite with your sister. I can't promise she will take you back. I never meet her, so I can't see her. But I can promise to give you the opportunity. We will work together for ten years. We will make each other stronger than either of us can be alone. I will make sure your hunters never catch you. I will use you, and you will use me."

"...Neat trick," Kuroka tried to make her voice teasing, but she failed. "It won't be enough to deal with anyone after me. You cut off your limbs because you couldn't cut the chains, right?"

"That's right," Eren nodded easily. "Without being able to use my Ki, I cannot fight most Ultimate Class beings. I can take them by surprise, but if I don't, I will just be a punching bag without Senjutsu."

"So you are useless right now," Kuroka said flatly, finally regaining some composure after the disconcerting sight. "You might be useless forever. You are not a Nekoshou. It will take years of constant training before you can even sense your Ki. Years more before you can use it. And decades to gain access to Senjutsu, if you ever can."

"Within a year, I will be better than you," Eren said plainly. "Within three, we will take over a faction with the True Longinus as its leader. Within five, I will be equal to a Super Devil. In seven, I will be leading a force with gods in it. In ten, I will be the fourth strongest being in this world."

"Only fourth," Kuroka laughed at the absurd claim. "Why not claim you can beat Great Red while you're at it? Can you do that in fifteen years? Twenty?"

"In eleven, I will be dead."

The laughter stopped.

Kuroka looked at the boy who calmly prophesied his own death with a wary eye.

"... Say I believe you," Kuroka said skeptically. "Not about the future, but about your talent. That still doesn't help me now, does it? It won't help me escape with you now. Unless you can tell me where the teleportation room to the human world is, you are useless to me now."

Once she knew that, Kuroka could leave this crazy boy behind and escape. She didn't know if the Dantalion spells had driven him to this madness and that silver substance was a weird Sacred Gear of some sort, but she didn't want to be stuck teaching a mad child Senjutsu.

It already had a bad name because of her, and she did not want to paint an even greater target on Shirone's back by having an actual mad sage running around.

"We cannot leave yet," Eren said simply.

"Why not?"

"Because if we leave before I show you my power, you will never work with me."

"Your power, nyaa," Kuroka asked with feigned casualness as she nodded toward the silver substance that kept him propped against the wall. Maybe he couldn't see the future but had a mind-reading ability. That made more sense. "What can it do?"

"Not this," Eren denied. "This is just a side ability for the moment until you teach me Senjutsu. Until you do, I must go big to compensate for my weakness."

"'Go big,' nyaa?" Kuroka snorted a laugh. "I guess you're hitting puberty early."

Eren didn't even flinch at her teasing, and Kuroka internally pouted.

This boy would be no fun. She could just tell.

"Place an observation spell on me," Eren said as the silvery substance started to carve into the stone walls.

"Why?" Kuroka asked waryly.

"Because I am going to put you in a ball to protect you," Eren said simply as more silver approached Kuroka. It did so slowly so as not to spook her, but she watched it warily. "You won't be able to see anything from inside if you don't cast the spell."

"I don't need you to protect me," Kuroka said with narrowed eyes.

"You will need to also reinforce yourself with Senjutsu and magic," Eren continued, ignoring her words as the silver substance started surrounding her in a sphere. "You can sense that I have no magic or similar power. I can't stop you if you try to teleport out. This is just to keep you safe for the demonstration."

He was right, of course. Kuroka could sense absolutely nothing from the boy except for a stronger-than-average well of Ki. Ki that wasn't moving.

She had no idea how he was doing this, but it wasn't magic.

The Stray Devil seriously considered just leaving or trying to knock this boy out, but she decided that once she learned his game plan, it wouldn't be too late to do that later.

So Kuroka placed the observation spell on Eren, as he had told her to, and the metallic substance encased her in a sphere.

She also secretly placed a clone, the only one she could conjure at the moment, near the boy so she could kill him if he tried anything.

If she could kill him.

That regeneration was greater than anything she had heard of, and she didn't know its limits. She risked revealing herself with any magic that had a good chance of killing him.

It took a few minutes of Eren digging his way to the surface from the dungeon, minutes he spent reinforcing Kuroka's sphere till it was tens of meters thick and firmly locked in place on the ground.

The Stray Bishop kept waiting for the betrayal, for the metallic substance to try and attack her, but it never did.

That worried Kuroka more than she cared to admit.

Hidden in that dark sphere, those minutes gave the Nekoshou time to think. Time she hadn't had in the days since she had killed her King and fled.

About the strange boy who claimed to see the future.

About her own future.

About her past.

About Shirone.

Kuroka wanted to see her sister.

She wanted it so bad.

Was Shirone alright? Did she know why Kuroka left, or did she believe the lies the devils were telling her?

Did Shirone hate her?

Did she think Kuroka hated her?

Watching Eren dig upward through her spell in that dark sphere, Kuroka suddenly felt her exhaustion catch up with her.

She hadn't eaten or slept in days. Always on the move, always running or hiding.

Maybe that was why she was going along with this madness.

Maybe she was just using it as an excuse to catch her breath.

It didn't matter.

Kuroka was alone now, crazy child or not. She had to care for herself and get stronger for Shirone.

So they could be together again.

Eren breached the surface, and silvery metal carried him out of the hole and between two buildings on the sprawling Dantalion estate.

He looked with blank, grey eyes at the monument of excess wealth and opulence as he spoke to Kuroka through the spell.

"I will kill everyone here, but this will attract every devil in the area. I've reinforced the teleportation room, so it won't be destroyed, but we must rush to it after I am done. You are faster so you will carry me. Just follow the trail."

"What are you going to do," Kuroka asked, transmitting her voice the same way.

"Before I do anything, I want to make sure you understand the deal," Eren said, ignoring her question. "We will use each other for our own purposes. Everything else is your choice. Do you understand?"

"I use you, and you use me," Kuroka repeated suspiciously as her clone caught movement from a passing guard patrol. "Whatever you are doing, you better hurry up, or you will be caught. I will not save you."

"One final thing," Eren said, unhurried. "I will never have children."

"...What?" Kuroka asked blankly, wondering what this nine-year-old boy was talking about.

"I want you to understand that I will never have children," Eren repeated. "This power will die with me. Do you understand?"

"Do you... think I want your children," Kuroka asked with incredulity and disgust. "You obviously cannot see the future. I don't go after kids. I want a strong man, thank you. Someone who can give me powerful kittens."

"What's that?" A voice called out in the night.

"Do you understand?"

"THE PRISONER'S ESCAPED!"

"Yes. Fine," Kuroka snapped impatiently as Eren was discovered. "I understand. Now do whatever you were going to do before you get caught again."

Though she said it quickly, Kuroka knew she was too late.

Anyone employed by a Pillar was at least a Mid rank devil. A human child stood no chance, weird power or not.

And she was right.

The guard's spear pierced the child's chest straight through the heart.

Clearly, they had orders to kill any intruders rather than capture them.

Kuroka, still in the dark sphere of silver, closed her eyes in regret.

Mad or not, she did not want to see a child die. But she also couldn't go save him without getting caught herself.

No, she needed to stay alive for Shirone.

No matter how much she might regret it, that was the world they lived in, and Eren Yeager was just another dead kid.

Just like all the other ones she had seen.

Though Kuroka was so tired, she readied herself to teleport away.

She'd use the mess of Eren's failed escape to head to another territory and hope for better luck leaving the Underworld there.

With any luck, nobody would ever know she was here.

Then her spell picked up Eren's words, and she opened her eyes.

With a spear through the heart and blood flowing freely, Eren looked Kuroka's invisible clone in the eyes.

"Then we have a deal."

Yellow lightning crackled along Eren's open wound.

The world exploded.

Even through meters of solid material...

Even underground...

Even reinforced with Senjutsu, Kuroka still felt the shockwave.

It threw her to the ground, and her sensitive ears were ringing from the noise.

Her clone was gone, and...

So were most living beings in the mansion.

Hundreds of lives snuffed out in an instant.

Kuroka scrambled to recast the spell that had failed in the explosion.

What had just happened?

It took her a moment to establish her spell and another for Kuroka to realize what she was looking at.

It was... Hell.

Like a nuclear weapon had gone off, the cataclysmic blast levelled the entire mansion.

Stone and metal remained here and there, all that was left of buildings that once stood four or five stories tall.

And everything was on fire.

Kuroka could not feel the heat from her protective cocoon, but she saw stone and steel melt and war. Heat and steam billowed out to the sky, and what remained of the nearby forest was already covered in raging flames.

The screams of the dying filled the night as those unfortunate to live through the initial blast burned alive.

And in the middle of it all was... it.

Towering hundreds of meters tall, bigger than even Great Red was supposed to be, the colossal humanoid stood in the wreckage of the Dantalion mansion.

Its skin steamed, red muscle glowing in the night, and white bone glimmered in the light of the fires.

Long dark hair hung over a face without skin. A row of teeth, too many to be human, stretched from one side of the head to the other without lips to cover them.

Green eyes stared down at the destruction it wrought from hundreds of meters up.

The titanic being took one step.

Only one.

The earth was pressed flat with that one step.

The Underworld rumbled with that first step forward.

All the screams from the survivors of the explosion, those desperate wails of pain and fear and confusion, died with that single colossal step forward that crushed the Dantalion estate flat.

Through her Senjustu, Kuroka knew only she and the... monster outside survived.

Kuroka feared she had gone mad.

Actually mad.

That the propaganda about Senjutsu had some truth to it, and her power had driven her to hallucinate.

Sure, this destruction was nothing compared to what some Ultimate Class devils could do, but for a human child to be able to do this?

A boy not even ten years old?

Kuroka realized she was laughing.

In disbelief at the situation.

In horror at the charred and crushed bodies.

At the absurdity of such a being disguising itself as a human child.

It looked more like the Devil than any devil Kuroka had ever known.

And it wanted her to train it?

What would that colossal be like if it was as strong, fast, and durable as a regular sage?

No, it would be even worse. Its healing was already insane.

If she taught Eren Yeager Senjutsu, would she create an unkillable giant? One who had no problem killing hundreds in an instant, even when he was just a boy?

Kuroka's mad laughter cut off as, through her spell, she saw something fall from the sky.

Suddenly, Kuroka teleported from her protective cocoon and caught Eren in her arms.

Her devil wings kept them aloft as the giant fell to the ground with an earth-shattering rumble.

It lay there, crushing what remained of the Dantalion estate under its enormous bulk, as Kuroka held Eren in her arms.

Absently, Kuroka noticed that it was already starting to dissolve into steam. Whatever had conjured it wore off quickly after Eren left it.

Eren looked back at her with those emotionless grey eyes.

Red muscle and sinew dangled from his exposed skin. It looked like it had burned itself into his flesh.

A row of curved markings now ringed his eyes, and his cheeks were sunken as if they were trying to imitate the teeth of that titanic... thing.

Kuroka was suddenly struck by an impulse. A wild, reckless idea.

She could drop this boy, this monster, and let him crash to the ground.

It might kill him. If not, it should injure him enough that she could finish him off while he healed. She had spells that would totally vaporize his tiny body, and she doubted he could recover from that.

She might be saving countless lives if she killed Eren Yeager right here and now before he grew any stronger.

Eren continued to watch her impassively as if he could see her thoughts.

... It was just an impulse, though.

Kuroka wouldn't kill a kid, even if he was a monster in human form.

That, and whether he could see the future or not, having a giant like that on her side would make her life much easier.

"I use you, you use me, right?" Kuroka said with a mischievous smile, and Eren nodded. "Then I am glad to work with you, Partnyaa."

In her tired state, she couldn't resist the pun.

There was still no way she'd want to have his children, though. He was way too young.

Although... the idea of massive kittens jumping over mountains did have a certain appeal to her, now that she thought of it.

Still, that was for the future.

Kuroka would see if there was any truth to his claims about his skill with Senjutsu and his ability to predict the future later.

Eren had just exterminated one of the last 32 Pillar houses. That was way worse than killing one noble devil.

Whether he did it to get to her or not, it didn't matter.

They were in this together, whatever 'this' was.

They needed to leave the Underworld. Now.

The Devil and the Stray's first meeting resulted in a mystery that puzzled the Underworld for years and hundreds of deaths.

Very few bodies were ever identified.

It was just the first taste of the destruction this world would feel from the Titan's Path.