Highschool DxD : Actually Satan

Second version of this chapter after i realised i fucked up pretty bad.

Also I added the Harem Tag since its pretty much Agreed upon by everyone Koneko is a paring for DxD world but I'm not really in favour of all the DxD harem.

So Akeno and Rias are not possible realistically at least not until the story is in final stages.

People voted for Tiamat x Mc pairing I'm not going to go against that decision.

I don't support it because Sakura x Mc was fixed from the start she's literally the Fanfic's poster and two girls from same world could be too much saturation but whatever

Aizen's redemption is easy but pairing is something I'm mulling over it has to be someone equally cynical and powerful.

You are welcome to give ideas Da Vinci is a good pairing though not my primary choice.

---

Leo exhaled slowly, shaking his head. "Yeah," he muttered to himself. "That'll do."

But then—

A sudden, violent pulse of pain surged through his body.

ZING

His vision sharpened, and for a moment, it felt as if something deep inside him had been violently wrenched apart.

A red warning screen flashed before his eyes.

[WARNING: SEED OF SATAN RESERVES CRITICALLY LOW]

[→ Reserves at 18% and dropping…]

[→ Immediate replenishment required…]

An unnatural hollowness spread through his core, a creeping sensation of emptiness.

[ALERT: MAGICAL ORGANS IN RIGHT HAND EXPERIENCING CATASTROPHIC FAILURE]

[→ 100% functional loss detected…]

[→ Magical output from affected area disabled to prevent worsening…]

His right hand felt cold, completely devoid of any energy.

It responded to his will, but there was a feeling of no magic in that area..

[ALERT: MAGICAL CIRCUITS OVEREXERTED – DAMAGE AT 50%]

[→ Severe inefficiencies in spell detected…]

[→ Long-term usage at current state is dangerous…]

A sharp, searing pain flared along his magical pathways before fading into a dull, throbbing ache.

[ERROR: CONCEPTUAL BACKLASH DETECTED]

[→ intervention in progress…]

[→ Mitigating damage…]

For a brief moment, reality flickered—as if the very concept of his existence had been shaken.

And then—

[ADVISORY: Neo Genesis exceeds safe operational limits. Usage not advised until Class 1 Physique is obtained.]

Leo exhaled, still feeling the phantom pain from the backlash.

I expected some backlash, but this is a bit much. Why the hell couldn't I predict this there was no feeling of exceeding my own limits ? And system, why didn't you warn me?

The reply came instantly, a flat, almost indifferent tone echoing in his mind.

[ There seems to be a misunderstanding. The Multiversal Chat Group is not a system designed for the preservation of the host.]

Leo frowned.

Huh?

[You are an employee under the Multiversal Charter. However, the system does not possess functions to actively prevent or warn the host regarding their actions that might cause self harm.]

Leo's eye twitched.

So you're telling me that while I may be here nearly blowing myself up due to a mishap and you're just gonna stand back and watch?

[The system is minimally involved in combat and does not dictate how the host handles their abilities.]

[Furthermore the reason of unclarity is due to your early-stage connection with the Seed of Satan, you lack full synchronization, which prevents you from accurately grasping your own limits.]

[Your new magical organs are also not in rhythm with your body as you have minimal practice with them]

Leo rubbed his forehead, irritation creeping in.

I'm essentially a rusher who developed too many abilities

You knew I'd struggle with my limits you could've warned me you know ?

[The system cannot assist in that regard. However, the host may purchase an Extension using Dimensional Currency to access advanced monitoring features. ]

[This feature will unlock after this mission.]

Leo's expression went blank.

...Wait. Are you seriously trying to sell me a DLC?

There was no response.

Leo sighed.

Of course. Of course, you are.

Leo was pulled from his thoughts by the soothing voice of Tiamat, her arms wrapping around him from behind in a gentle but firm embrace.

"Are… you okay?"

Her speech was still slow, deliberate, as she was getting used to speaking.

Leo exhaled, pushing aside his irritation with the system. "Ah, yeah. Just a minor miscalculation."

He shifted slightly, intending to step away, but the moment he moved, Tiamat tightened her hold.

"...Okay," she murmured simply, pressing her cheek lightly against his back.

Leo paused, then huffed in amusement. It seemed like she wasn't planning to let go anytime soon.

Aizen, who had been observing silently, raised a brow before offering a mock casual salute.

"Well then, I'll be heading off to the North as planned," he said, his voice smooth and unbothered.

"Now that we have one less target to worry about, my work just got easier. If I require your assistance, I'll send a message through Kidō."

The space in front of Aizen unzipped like stitches being undone, the air peeling apart to reveal a swirling black void—a Garganta.

Leo raised an eyebrow. "So this world has something like the Garganta too?"

Aizen, already stepping toward it, glanced back with amusement. "No. I'm simply projecting an illusion over the world."

He gestured toward the tear in space,. "By weaving the illusion into reality , I create a miniature fissure in it—allowing me to form something similar temporarily."

Leo's expression stiffened. That wasn't an ability Aizen originally had.

Unless…His eyes narrowed .

"Bankai...?"

Aizen's smirk turned into a full-blown grin, nodding as he stepped into the void.

"Bankai."

---

After Aizen vanished into the void, Leo turned his attention to Tiamat, who still had her arms wrapped around him in a firm embrace.

"Would you mind releasing me?" he asked, trying to sound casual.

Tiamat tilted her head slightly, her grip tightening just a bit. "Hmm… I… would."

Leo blinked. "That...your not supposed say that."

She simply hummed, resting her chin on his shoulder.

Leo opened his mouth to argue, but movement from the pitch-black pond caught his attention.

He immediately seized the opportunity.

"Oh look, Fury's waking up. I should go check on him."

Tiamat hesitated, her grip lingering before finally letting him go.

Leo quickly stepped away, approaching the stumbling figure of Fury, who dragged himself out of the dark waters like a man who had seen hell and barely crawled back.

His breaths were heavy, and his entire body trembled slightly.

His features were... younger, his old age seemingly peeled back a few layers.

But exhaustion was written all over him.

He groaned, running a hand down his face. "Feels like I just got my ass beat a thousand times..."

Leo smirked. "Good news, spy supreme. That means it's working."

Fury shot him a tired glare. "If it worked any better, I'd be dead."

Leo chuckled, but his gaze shifted back to the pond.

Hope was still submerged, taking longer than Fury.

Unlike Fury, her physique had already been supernatural—her evolution would be different.

Looks like I've got time before she wakes up.

Leo rubbed his chin and then decidedthe next course of action.

"Alright, let's do an assessment. The sooner I'm done here, the sooner I can fix my own problems," he said, turning to Fury.

"First thing—try punching me with all your force."

Fury raised an eyebrow before letting out a short chuckle. "Okay, Mr. Satan. I'll do my best."

Cocking his arm back, he threw a punch with all his might.

A sharp boom echoed as the air itself split from the force.

The strike landed cleanly on his torso—only for Leo to remain completely unmoved.

Leo nodded in approval. "Hmm. That's solid attacking power."

He mentally gauged the strength.

If he had to scale it in terms of raw stats, it would be somewhere between E and D—with E being ten times the maximum human strength and D being 10 times that of D.

That meant Fury was already leagues above his past self.

But that wasn't the most important part.

The true purpose of the Sea of Life bath wasn't just raw power—it was transformation.

Fury was no longer just a human in the modern sense.

The concept of his body had shifted.

He was now an Old Human—one from the Age of Gods.

And that changed everything.

In Nasuverse things were different for humans in different ages.

Unlike modern humans, who had a strictly biological framework of organs, blood, and nerves, Old Humans existed under different metaphysical rules.

Their biology was shaped by collective human belief and mysteries, meaning their bodies followed principles that defied standard logic.

One of the biggest shifts was his magical foundation.

Unlike most Marvel humans who borrowed magic from external sources—dimensions, entities, or artifacts—Fury could now generate ether on his own.

His body had developed an organ specifically for that purpose, meaning he was now one of the most magic-attuned humans in his universe.

Even more interestingly, his brain was no longer a vital organ in the traditional sense.

Destroying it wouldn't cause instant death—only fatal blood loss over time.

That alone made him significantly harder to kill than any normal human.

And all of that was besides the fact that Fury now possessed very very Minor Divinity and traces of True Ether woven into his being.

His potential at this point was comparable to that of an Omega-level mutant who has yet to master his abilities.

Fury, finally settling into his new body, cracked his neck. "Alright. So, are you gonna teach me some magic now?"

Leo looked at him, dead serious. "I don't know any."

Fury blinked. "...Do you think I'm stupid?"

Leo sighed. "No, I do not. It's just a normal assumption to think I have magical knowledge or theory to teach. "

"But I don't. I'm simply naturally adept at creating magic due to certain traits and skills I have."

Fury's expression instantly morphed into one of absolute exhaustion—his entire face radiating a silent, I can't deal with this shit anymore.

Leo, unfazed, continued. "But honestly? I don't think you really need to think too hard about acquiring magic."

Fury narrowed his eyes. "And why is that?"

Leo smirked. "Because you're a teeny, tiny bit a descendant of Tiamat now."

Fury blinked. "...What?"

Leo shrugged. "That means you have divinity—even if it's incredibly minor. And that means, eventually, you can just form your own unique magic with simple belief and imagination."

Fury groaned, rubbing his temples. "Well, that was not my expectation... but I guess it is what it is."

Leo nodded. "True, it is what it is. You can rest up and try to meditate—see if you can draw out your magic naturally."

Before Fury could respond, Hope finally emerged from the water.

Leo grinned. "Hey, you. You're finally awake."

Hope rolled her eyes at the obvious reference but didn't say anything.

Like Fury, she was dressed in just her underwear to avoid soaking her normal clothes.

She stepped out, running a hand through her hair to shake out the excess water—

—then, in an instant, she used magic to dry herself completely and in the next she was dressed fully.

Leo raised an eyebrow. "Your upgrades are nice. You're definitely way stronger than before."

He could tell at a glance—her speed, aura, and presence had increased nearly tenfold.

In terms of raw physical strength, she could likely destroy a large building with ease.

And considering she was already capable of city-level destruction with magic before with some preparations , she could probably flatten an entire city effortlessly now without straining too much.

Leo smirked. "Also, Fury—if you want to learn magic, I think she should be a great teacher."

Fury looked at Hope, then back at Leo. "...Yeah, that's a great Idea."

Leo turned his gaze toward Tiamat, who was crouching down, poking at a squirrel with a somewhat mournful look for being ignored.

She wasn't actually being ignored—just… not the center of attention.

And considering how easily Leo had allowed her advances, she had gotten used to being glued to him.

Watching her like this reminded Leo of DxD Tiamat, the dragon currently sealed away in his Magical Poke Ball.

And that gave him an idea.

Without hesitation, he sealed the remaining water from the Mini Sea of Life into a pocket space—just in case he needed it later.

Then, he teleported next to Tiamat and casually poked the back of her head.

She blinked, tilting her head in confusion, and even the squirrel she had been tormenting mirrored her reaction.

Leo didn't acknowledge either of them and turned toward Hope and Fury. "I'm taking Tiamat for some personal problems with my body. I've got some issues I need to fix, and she has the tools I need."

A beat of silence followed.

Hope's eyes narrowed slightly. "….Phrasing was awkward"

Fury, without missing a beat, gave a solemn nod. "Very."

Leo snorted. "You've already started kissing up to your teacher, huh?"

Hope smirked slightly, while Fury just shrugged.

"I'm a fast learner."

Leo shook his head, lifting a hand.

A Bounded Field formed around them, infused with the Divinity of Venus. "This will keep you both safe. Anyone trying to enter with ill intent will be teleported straight to Venus. "

"Carry on with your lesson."

And before either of them could protest further—

—Leo casually picked up Tiamat like a sack of potatoes, even if an oversized one and vanished.

---

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Stones and Reviews please