Author's Note: I want to apologize for the delayed update but unfortunately, there was a medical emergency that prevented me from delivering the content on time but I'm eager to get back on track with the regular updates.

As he examined the figure clad in the visage of the Mona Lisa that stood before him, he stated the most obvious question.

"Why are you here?" Batman questioned, his voice low and probing.

The woman, always smiling, replied, "The question of the ages. Why are any of us here?"

The tensing of the dark knight was no longer in preparation for battle but an annoyance. He only looked on at the woman, his expression unreadable, even beyond the cowl.

Her smile became even more cheeky.

"I'm here for the thrill of innovation, the pursuit of knowledge, and the sheer joy of existence. What about you?"

Batman, ever guarded with his secrets, replied with a stoic, "I have more focused pursuits."

Intrigued, Da Vinci pressed further, "And what might those reasons be, my dear Master?"

...

His reluctance to share any personal information was palpable.

Da Vinci chuckled, "Ah, the mysterious type. Very well. But I'm curious, how well-versed are you in the art of magecraft?"

Bruce raised an eyebrow she couldn't see. "I know about it."

"Ah, a man of brevity," Da Vinci remarked. "But do you truly understand the intricacies of magecraft? The manipulation of mana, the recreation of phenomena, the goal of all magi?"

The question lingered in the air like an uninvited specter, prompting the recesses of his past, a journey back to the haunted halls of his training.

Bhutan, a rugged terrain where he spent years honing his mind and body to the peak of human potential. Among the various trials, one stood out — three months with the elusive 10 Eyed Men. A hypothetical study on the elimination of "demons," an esoteric term that masked a darker reality.

The Thogal Ritual, an advanced meditation meant to simulate death and rebirth. The sensation of slipping into the void, a sensation of losing everything only to be reborn anew. It was a masochistic process, a form of torture he willingly endured to unlock the depths of his potential.

Weeks in isolation within a lightless cave, an utter hell that tested the boundaries of his sanity. A journey into darkness that demanded a toll, but it was through this suffering that he gained a profound connection with his "soul", mind, and body.

He recalled questioning the necessity of such extremes. In his global travels, he encountered other paths that yielded similar or superior results. The time spent with Boba Tomar in Joshimath, where he perfected body healing meditation, seemed a more efficient route.

As part of his quest to become Batman, he studied under an academic nomad capable of controlling his own mind. The somber memories resonated with the weight of sacrifices made in the name of a relentless pursuit.

Batman thought about the "basics" he knew.

Controlling the flow of his "chi" was a concept he had mastered in the Far East during his training. But magecraft delved into a realm beyond mere physical discipline.

He remembered his encounters with the supernatural—the Dead Apostle "The Monk", "Deacon" Blackfire and the yearly resurrection of Solomon Grundy.

He knew that it was a complex and powerful study that could allow one to manipulate natural forces.

He knew that it required a deep understanding of the occult and a strong will to master it. He was aware that it was something that could only be achieved through years of study and practice...

His earliest experience with the mystical arts, a venture with Zatanna to halt a demon's rampage in the heart of New York, flashed before his eyes.

Batman contemplated the threat that this being might pose if she wasn't like Boston and this Holy Grail War situation was unpalatable to his mission, already thinking of ways to countermeasure.

The atmosphere hung heavy with unspoken histories.

The Mona Lisa responded with an air of nonchalance. "A lot it would seem. Only theoretical perhaps? Or-"

Batman, however, was not one to easily lose focus on a possible source of information. "What is this "Holy Grail War"? What is its purpose?"

A sly smile played on Da Vinci's lips. "Oh? Academic curiosity?"

In the center of the shipping container, Batman's stern gaze fixated on the Servant, his stoic expression demanding answers. In response, she assumed the role of a lecturer, as if a seasoned professor imparting knowledge to an eager but inexperienced student.

"Let me enlighten you then," she began, her tone carrying an obviously artificial air of wisdom.

The air shimmered and danced with hues of mystical energy as two sets of seven chess pieces materialized, one full of pawns with one uniquie ( familiar) exception, another unreconizable to the game but except a knight piece. The bizarre chess pieces, elegant in their shape if nothing else, arranged themselves on an unseen board suspended in the air.

"The Holy Grail War is a grand competition orchestrated by magi who hunger for the coveted Holy Grail. Seven Masters, each chosen by the Grail, summon seven Servants—heroic spirits, like myself, brought forth from the Throne of Heroes by the will of the World."

She paced gracefully. "A Servant, my dear Batman, is but an emanation, a pseudo-copy of a heroic spirit's main body. Summoned by ritual, we serve as a magus's sword and shield in this deadly contest in the containers designated as Saber, Lancer, Archer, Rider, Caster, Assassin and Berserker."

As the weight of her words hung in the air, along with the frown he expressed at the mention of Assasin, she continued her lecture. "You see, the magi are not the ones doing physical combat. That's where Servants come in. We are their primary tools in the Holy Grail War, engaging in battles with other Servants until only one Master-Servant pair remains standing."

The illusions intensified, the chess pieces engaging in a mock battle, conveying the stakes of the conflict.

She paused, inviting Batman to digest the information. "The Holy Grail itself is the grand prize, capable of granting any wish. It's not the Cup of Christ, as many believe, but a potent artifact that can alter reality itself. The knowledge we Servants possess, combined with the magus's own, is the key to navigating this treacherous contest."

She anticipated the questions that brewed within Batman's mind and addressed them before they were uttered. "Yes, it's a competition between life and death. Yes, it's as perilous as it sounds. And no, the Holy Grail War is not a quest for the divine artifact we've come to know in tales. It's a conflict for the fulfillment of desires."

As the last pieces fell away, leaving a scholar and horn and winged pawn standing, a golden cup rose in between them.

As she concluded her explanation, Da Vinci's eyes sparkled with a mix of amusement and seriousness, waiting to gauge Batman's understanding of the arcane contest now thrust upon him.

Batman's sharp gaze was fixed on the living legend, his inquiry straightforward. "And what do you want?"

With a whimsical smile, her response echoed through, repeating an earlier question as an answer. "Academic curiosity."

...

A pursuit of knowledge, an insatiable thirst for understanding. While Batman was no stranger to unusual motivations...

Still, her inhuman nature may be fooling his cold reading capabilities.

One of the unspoken benefits of Batman's near-perfect mastery of body language was his ability to convey thoughts without uttering a word. The subtle shift, the slight furrow on his lips—

The response to the unasked question lingered in the air.

Da Vinci, noting Batman's contemplative silence, decided to address the unspoken question hanging in the air.

"Command Seals," she began, her tone carrying the weight of knowledge. "They are the very linchpin of the Master-Servant relationship in a Holy Grail War. Consider them the magical contract that binds us. A Master is granted three absolute commands, represented by these seals."

"Absolute commands?" he mused, considering the implications.

"Yes," Da Vinci continued. "These command spells are a Servant's shackles, ensuring obedience. They can be used strategically, providing a Master with a means to enforce their will, and, if wielded judiciously, even enhance a Servant's capabilities."

As she spoke, Batman's thoughts turned to the sensation he felt during her summoning—the burning on his hand and the appearance of ritualistic tattoos. He steadily removed the gaulet once again. It was a visual confirmation of the contract that tethered her to his will.

He felt a twinge of discomfort at the idea. The notion of imposing his commands on even a spectral being conflicted with his principles... despite how useful it could be in a situation where things turned south.

Unfazed, Da Vinci quipped, "Ah yes, the slow removal of the glove was suitably dramatic. It even had me wondering if you were really my Master."

His irritation at her comment would have been evident in any other situation, but he couldn't ignore the gears turning in his mind. The revelation about Kiritsugu Emiya's presence in Fuyuki snapped the pieces into place.

The detective within him had made an intuitive leap, connecting the dots. The Holy Grail War—the only plausible reason for Emiya's emergence from hiding...

What was once a tense standoff has become a laxative conversation between two different people. Most people, even the most stoic, would be befuddled.

He could only feel exasperation.

It was another Deadman situation instead of Gentleman Ghost.

He understands that he should be more relieved at both the lack of conflict, a more pragmatic reasoning is that it would be less difficult (dangerous) with nothing obstructing the mission.

It was still annoying.

He still kept on kept himself ready for a moment's notice of hostile intent but based on their countenance and their supernatural capacity via the violation of physic, they truly were wanted a "civil conversation"

"Saber, Lancer, Archer, Rider, Assassin, Berserker, Caster."

"Indeed, seven classes for seven masters. And you, my fateful accomplice, has the privilege of having called upon Servant Caster."

"A mage then?"

"Amongst other things, one need not follow the path of magecraft for their works to be considered 'magical'. Whatever moves and touches the heart is surely as powerful as any ritual or enchantment."

"An artist against a legendary hero? I fail to see the benefit in aiming for it."

"Oh but are we not all actors in this grand stage that is life. Siegfried the hero is but one actor against many. Edmond Dantes. Hamlet. Behind great heroes lies the brush and pen of a skilled storyteller. I as a caster happen to be suited to create things that can match the greatest of heroes. Such is my role in this stage of Fuyuki."

"And what of my role?"

"That remains to be seen, after all, it would make for a boring play if we spoiled the ending for the audience. Even if it is an audience of one."

In the midst of the banter, Batman's mind was already at work, assessing the situation and considering potential allies who could shed light on the supernatural entanglement he found himself in. He needed someone who understood the intricacies of magic, or magecraft as they would always stress, someone he could trust implicitly.

As his mental Rolodex of magical experts spun, names flitted through his mind.

John Constantine?

He immediately dismissed the idea.

Constantine, while undoubtedly skilled, was akin to dancing with chaos and disaster itself.

Jason Blood?

The name lingered for a moment longer before it too was dimissed. The recluse would likely be more interested in his own affairs, and reaching him could prove a challenge.

Then, a more comforting name emerged—Zatanna.

From when he sought knowledge from John Zatara, he delved into the very concept of ancient mysteries. Those lessons lingered in the recesses of his mind, forming a foundation for his understanding of the arcane.

'You can't punch magic. You can't outthink magic. The only rules are the ones people trapped themselves in making.'

He couldn't help but reflect on the years he spent steering clear of the supernatural afterwards, seeking a place within conventional justice systems*, unaware that his battle would eventually lead him to confront the very forces.

In the dimly lit confines of the repurposed shipping container, Batman stared at the spectral being that was called. Their banter had given him a bit of informative discourse, but he wasn't one to rely solely on words.

"I'm calling in an expert," he declared.

The ever playful spirit, quirked an eyebrow. "Oh, you don't trust me already? I'm hurt, Master."

Batman ignored the jest as he moved to some machinery on a desk near him, his gloved fingers deftly manipulating a makeshift transponder. One of the first things he set up was a communication relay.

The call was directed to a person he trusted in matters of the supernatural—Zatanna Zatara.

"Long time, Bruce. I know you're not calling me just 'cause you missed me," Zatanna's voice … trembling (?) voice flowed through the communication link.

He had to hold his instinctive response to telling her off on the use of civilian names and the instinct to ask if she was alright. Forcing himself to remember she could take of herself.

"Zatanna... What do you know about 'Heroic Spirits'?" Batman inquired, getting straight to the point.

"... Bruce. What...exactly...have you gotten yourself involved with?" Zatanna's tone shifted.

"Zatanna, that's not important right now."

"I think it's pretty damn important considering the mess you've dragged yourself into. Please tell me you didn't summon some sort of super-criminal through a bond of coincidence or tie of En like... Jack the Ripper or something?"

He ... hesitated, glancing to the side, at his newly summoned Servant.

Zatanna, not one to miss a beat, read between the lines. "Are you Jack the Ripper?"

Da Vinci, with her characteristic humor, held up a V-sign .

"She's not Jack the Ripper. Also, the name implies they should be inherently heroic," Batman clarified.

Zatanna scoffed at the notion. "Too modernistic, Bruce. Think of the ancient world Greek-style definition."

"And your first thought was Jack the Ripper? Zee. What exactly are you implying?"

"Alright, from the top. Seven Masters, Seven Servants, each pair vying to claim a wish by defeating the others."

"That's about it. Usually they leave out a few spots to be filled by random people. Easy to work around and easy to beat. Though obviously they couldn't have foreseen the rise of modern heroes in the 1800's."

"And you have never mentioned it before... why?"

"Look, the Holy Grail War never worked out and the most my dad ever told me about is that it took half a century for each attempt. He told me he participated in the previous one when he was young, but never specified. I could be looking at 10 to 20 years away. I thought I had time, okay?!"

After a moment of contemplative silence, Batman shifted the conversation to a more immediate concern. "What can I do to prepare? How do I fight?"

"Zatanna... I need to know how to prepare for this Holy Grail War. What can you tell me?"

Zatanna took a moment to consider her words. "Protection is key. Wards, sigils, anything that can detect, deflect or reduce magical attacks or tampering. It's a battleground. Control it accordingly."

Batman pressed further. "Can you guide me in creating these wards? The ones you use? I need to be ready."

He noted how his "Servant" perked up at that inquiry.

"I can send you the basics. A crash course, which might as well be a thesis as you've always been a quick study. But..." She hesitated.

"But what?".

"Batman - Bruce, I... I can come to you. Help you in person," Zatanna offered, her voice softening.

Before he could berate her for the use of civilian names on comms, Batman, ever the detective, caught the subtle tremor in her words.

"Zatanna, are you in a state to assist right now?" he inquired, a note of genuine concern in his voice.

She hesitated again, and for a moment, the air crackled with unspoken tension. "I've been better," she admitted.

Batman's eyes narrowed. "What happened?"

"It's... complicated. Dark forces are at play, and I got caught up," Zatanna confessed.

A moment of silence hung between them.

Finally, Batman spoke, his voice measured but filled with gratitude. "Zatanna, I appreciate the offer, but I can handle this. Send me the information. That's all I need."

"I'm fine, Bats. It's just... complicated. We'll talk about it when I get there when I get the chance," she interjected when the silence grew too long.

"...Be careful, Bruce. And remember, you're not alone in this."

He didn't say anything before he hung up.

Batman absorbed her advice, his mind already working on how to integrate this new knowledge into his existing strategies.

It would seem that he would be back to working with someone again.

"I'm going to need a better name than Caster if we're going to work together."

"Alright, you tell me yours and I'll tell you mine~"

"..."

The clues were there, scattered across the conversation and the very essence of the Servant stood before him. The "Universal Genius" phrase, the idealized Mona Lisa in living form— there were only 2 answers. Either the summoning has implications based on humanities perception or history got something wrong big time.

As his mind churned with information, an unexpected internal sensation began to manifest.

A dull ache, a subtle drain, a discomfort—it coursed through his body like an unwelcome undercurrent. Instinctively, he paused, his mind shifting from magical defenses to this newfound anomaly.

What's this sensation?

From the corner further away from the desk, previously fidgeting with the tools on the desk, she observed with a bemused expression. "Ah, your karmic bond is surprisingly well done, Master, despite the accidental summoning too. You get more and more interesting "

"Explain."

Da Vinci's tone took on a conversational lilt, "When a Master and Servant form a connection in the Holy Grail War, there's a subtle exchange of energies. It's the metaphysical tether that binds us. You feel my presence, and I feel yours. A side effect, if you will."

He quickly put together the pieces. "This connection... there is more to it isn't there? And Karmic Bond?"

"Well, of course, it is called a Karmic Bond. Though you probably weren't there when it was said, part of the incantation required to summon me would be 'my will creates your body, and your sword creates my destiny'. Your essence, not just the power of your soul, but your very self tethers me to this world, and our actions in this grail war shall define your fate at the end of it. Cause and effect, yin and yang, a brush and a canvas."

After that tidbit, Batman leveled a direct question at his Servant companion, "What other abilities are you willing to reveal?"

Da Vinci, ever playful, responded with a quizzical look, "Why, Master, are you planning to pick and choose your favorite skills?"

Batman arched an eyebrow, showing no amusement. "Just the relevant ones," he replied.

Da Vinci chuckled before giving a more serious answer, "Very well. As a Caster-class Servant. My class' abilities lie in magic, artifice, and a few unorthodox inventions. With genius though, I've got my share of surprises up my sleeve."

Batman nodded, content with the response ... but not fully satisfied.

She, in turn, posed the same question to her: "And what about you? What can you do, Batman?"

...

With a stoic expression, Batman reluctantly listed some of his well-known skills, "Above average physical abilities and advanced equipment."

Da Vinci... gave an impressed attitude despite the lacking description. "Ah, you're a polymath in your own right, Master. Now, if you're interested in my more intricate abilities, you can use [Master Clairyovance] to focus on our Karmic Bond. It should provide you with insights into what I can bring to the table."

He... would qualify as a polymath, which only added the dread of how she could infer that. He shuddered as he thought about the implications of such a bond. He took a deep breath and prepared himself for what he had to offer. Still, Batman, though skeptical, acknowledged her suggestion with a nod as he noted the "fellow polymath" statement.

The "Universal Genius"

The Mona Lisa was brought to life.

He could only piece together the enigma standing before him. He knew she was a mystery, but he would make sense of it. He was determined to uncover the truth.

As Batman hesitated, his mind working through the implications of this revelation, the woman's eyes sparkled with a mischievous glint. She could practically read the gears turning in his mind.

"Leonardo Da Vinci," Batman finally spoke, a statement more than a question.

A broad, satisfied smile crossed Da Vinci's face. "Bingo! You got it, my dear Master. Now, any questions you might have?"

The straightforward acknowledgment left him slightly off-balance. Da Vinci's openness, her willingness to be recognized for who she was, felt like a deviation from the norm.

"But... you're being surprisingly... straightforward," Batman observed, his detective instincts ever alert.

Da Vinci chuckled, "Why play mysterious when I can save us both the trouble? I'm here to win the Holy Grail, but that doesn't mean we can't have a bit of enjoyment along the way, right?"

Details about Da Vinci's abilities, experiences, and even snippets of her past were laid out before him.

As the ... experience concluded, he made a silent decision.

It was time to return to the hotel suite, assess the events of the day, and formulate new strategies for the unpredictable path that lay ahead.

A battle within him unfolded. On one side stood his innate paranoia, urging him to remain vigilant, to secure every loose end. On the other was pragmatism, whispering that he now had a knowledgeable ally in Zatanna, and the apparent absence of hostility from Da Vinci herself( and how the former would ensure nothing would come of the latter if it was a ruse and he didn't make regular communications).

"I'm leaving," Batman declared, breaking the silence that lingered in the makeshift base. "I'll be back tomorrow night."

"Da Vinci" voiced her concern. "It's dangerous out there. Without a Servant, you're an easy target."

Batman, however, was resolute. "Based on what you've told me about Servant classifications and the dynamics of the Holy Grail War, the same applies to you just as much."

"I'll take the risk."

With that, he made his way to his escape vehicle he had prepared for the possible confrontation.

In the corner of the makeshift base, partially concealed under a tarp, rested the heavily modified jetblack Kawasaki Ninja ZX-11. The original model, a high-performance machine in its own right, had a 1052 cc four-stroke, DOHC, inline-four engine capable of reaching speeds up to 290 km/h.

It was retrofitted with a prototype electric engine to reach higher speeds at less cost and a quieter movement. The quiet hum of the electric motor replaced the thunderous roar of the conventional engine, turning the once roaring beast into a silent predator.

In one smooth motion, he swung a leg over the modified machine and engaged the ignition. The bike responded obediently with a rush of movement out of the prepared exit.

As Batman maneuvered the motorcycle out of the concealed base, Da Vinci observed.

In the dimly lit chamber, Da Vinci allowed herself a sly smile. "Quite a ride you've got there, Master. I'll make a better."

And with that, the Universal Genius, Leonardo Da Vinci, turned her sights first to the car pieces laying around before she looked further around the base.

Leonardo Da Vinci immediately transitioned from observer to architect. The modest shipping container, now a canvas for her artistic magecraft, awaited transformation into a suitable mage's workshop. Her objective: create an environment conducive to both her own endeavors and the potential collaboration with her newfound Master.

With an almost instinctive command, she activated her Magic Circuits.

Sending forth a wave of Od, Da Vinci began to scan the surroundings.

The information flowed through her as every object, every container, bore a unique resonance within that she could decipher.

Rocks, cobble , asphalt … containers unfolded in her mind. The 40-foot containers, with their dimensions of 8 feet in width and approximately 8.5 feet in height. The 20-foot variants, spanning a length of 20 feet, found its place in the enigmatic dance of geometry.

In the realm of magic, every object told a story through its magical imprints. Abnormalities, hidden energies, and potential threats would reveal themselves to Da Vinci's keen perception.

With this detailed analysis, Da Vinci's next step became apparent. She envisioned a bounded field, a protective barrier woven from the very fabric of magical energies. Understanding the natural flow of mana within the container, cut off the outside from the inside against external intrusions.

Then she extended consciousness beyond the steel confines of the container. It flowed seamlessly, like a river of thought navigating the invisible currents in the space that it occupied.

A lesser-known aspect of Magic Circuits came to the forefront: the ability to record, store, and replay information. Da Vinci's consciousness became a living archive of her ideas, schematics and works. With this Da Vinci orchestrated the transformation of the shipping container into a mage's workshop.

To those who would have been there to observe, if there were any, it was a brief lightshow. Blue light crackled across the Mona Lisa's body. Her long hair flared...

In a single great pulse, energy shot out, crackling along every surface, dancing across walls and ceilings, and carrying on well past the bounds of the room. Even the open spaces were flooded with energy, leaving sparkling motes hanging in the air for the briefest instant before they faded away like melting snow.

Millions of complex functions come together, drawing data from decades of experience to form a fundamental expression of alchemical transmutation.

The echoes of her magic reverberated within the steel walls, marking the inception of a one of a kind collaboration between the greatest polymath from the Renaissance and the most skilled man of the modern era.

After he swiftly navigated the labyrinthine streets of Fuyuki to his destination: his hotel suite.

Arriving near the area of his suite, Batman seamlessly transitioned into the shadows with his bike, ducking into a dark alley concealing his equipment in a specialized backpack. The motorcycle found refuge in a secluded alley, secured with a state-of-the-art lock. With his personal vehicle hidden, the Dark Knight, now Bruce Wayne entered his suite.

Reflecting on the summoning of Leonardo Da Vinci, Batman found himself genuinely baffled for a bit. A famous artist in the idealized body of their famed art piece, manifested through magecraft, added a layer of complexity to the already enigmatic Holy Grail War. He pondered what John Giovanni Zatara would make of this surreal collaboration.

Switching mental gears, Batman engaged in a clinical assessment of the situation.

Objective: Hunt Kiritsugu Emiya. Status: Unknown.

The initial reason for Batman's presence in Fuyuki. Kiritsugu Emiya.

Serial killer apprehended during patrol. Identity

A fortuitous intervention unexpectedly triggered the summoning ritual, bringing forth the iconic Leonardo Da Vinci.

Accidental summoning of Da Vinci. Servant classification: Caster.

The accidental collaboration with Da Vinci, now classified as a Caster-class Servant, thrust Batman into a "War" he didn't start.

Batman contemplated a shift in his approach, recognizing the need for a specialized loadout tailored to the demands of the Holy Grail War.

Logistical adjustments are necessary. Full loadout required.

He decided to call Alfred.

The Batwing would embark on a supply delivery to Fuyuki via autopilot.

Alfred voiced his "concerns" regarding violating Japan's airspace.

"They barely skirt the line as it is, 'the colonies,' here in Gotham" quipped Alfred, his British wit ever-present.

Batman, undeterred, asserted the superiority of Wayne Tech's stealth technology. The Batwing, the epitome of aerospace engineering, would navigate Fuyuki's skies unnoticed, a silent guardian in the night.

"To be on the safe side, arrange care package deliveries and for Oracle to align satellites for mana detection."

She would synchronize satellites to a specific frequency capable of detecting mana fluctuations.

"Arrange the purchase of Hyatt Hotel's parent company. Renovation for base construction to cover the other supply shipments I'm requesting."