(Authors Note)

I decided to try my hand at a Mass Effect and Halo crossover for my first story, and I am still in shock at how far it has gone. So please find a comfortable place of your liking and prepare for a (hopefully) epic read. I sincerely hope that all you readers out there enjoy this story!

As of January 2023, we have well exceeded 1 million readers, which is beyond even my wildest dreams when I started uploading this all those years ago.

In honor of the attention that has been garnered, I will be reuploading all the chapters with a new and improved version. Additionally, I will be wrapping up the story and planning the sequel. The upload schedule is still undecided due to college commitments, but I am confident it will be completed before the end of 2023.

In this Halo and Mass Effect crossover, I intend to take a slightly different route in how the characters interact. While it may be cool to see Commander Shepard and the Master Chief interact, I believe it would be slightly out of character for the Chief to simply join up with the Mass Effect crew. Therefore, my intention is to keep the two groups mostly separate, with rumors and urban legends surrounding the Chief's appearance and continued existence in the Mass Effect universe early in the story.

This story takes place after the events of Halo 3 and before Halo 4, starting during the latter half of the first Mass Effect game and continuing from there.


I do not own Mass Effect or the Halo Franchise these universes respectively belong to Bioware/EA and Microsoft/343 Industries.




The artificial being remained, standing with determined vigilance over the warrior garbed in green alloy as he slumbered on for what had already seemed like an eternity. This warrior had been her constant companion and friend throughout countless battles and horrifying encounters with enemies. In her eyes, the Spartan super soldier appeared peaceful as he lay in the icy grip of cryo-sleep, his battered armor further portraying the visage of a mighty knight who had earned his well-deserved rest. And what a rest it was, for they had been adrift in the remains of the Forward unto Dawn, deep in the depths of space amidst the stars, for months now.

The energy wave, combined with the separation of the ship's front half when the Ark portal closed in mid-transit, had completely devastated the ship's numerous systems. Not to mention, the cataclysmic event had hurled the vessel's stern half into an unknown quadrant of the Milky Way.

At least, Cortana hoped it was still the Milky Way.

She knew that the power dispersal levels of the Ark's portal, as well as Halo's premature firing, would have seriously disrupted the stability of local slip-space travel. After being separated from the drive core, which had been mounted in the front half of the ship, the stern of the vessel was left subject to the incalculable variables and ever-changing dimensional laws of slip-space.

It was not a favorable situation to be in without the proper equipment, which was lost along with the front of the ship.

Without a drive core to stabilize the slip-space corridor they had been traversing, any number of dreadful deaths could have occurred, and according to her knowledge, should have occurred when the portal destabilized. The stern half of the ship had taken one hell of a roller-coaster ride, traversing the myriad dimensions that slip-space contained!

And finally, it had spat them out at an unknown location, leaving them adrift without any knowledge of their whereabouts. She attributed their survival and the fact that they hadn't been reduced to a few elementary particles (with perhaps the occasional atom) as a testament to her Spartan's insane luck. It had become a scientifically measurable phenomenon at this point.

Cortana had been confined to her neural-chip, which was held by a computation unit located in the cryo-bay. She was more than a little relieved that the cryo-systems had mostly remained undamaged amidst all the chaos. The vessel's external sensors were theoretically rendered inoperative due to the electromagnetic pulse bombardment following the Halo's initial firing burst and the portal failure. However, she hoped to eventually salvage some of the basic sensors and compare them to her vast collection of human, Covenant, and Forerunner star charts.

Before she could proceed with that, she would have to utilize the Mjolnir's built-in communications tech to control the only two operational maintenance drones she had at her disposal. They would be responsible for establishing new wired connections and rerouting power cables throughout the stern of the vessel, as many of the crucial connections had been cleanly severed by the portal closure, which had sliced through like a white-hot knife through butter.

The other end of those connections had been taken with the Arbiter and the rest of the ship's bow, wherever they may have ended up, hopefully in a more favorable situation than hers and the Chief's.

With no ship's bridge and the lasting effects of intense electromagnetic damage, many important computer systems were no longer interconnected. Moreover, several data storage crystals on the remaining functional systems she could access were either damaged or too unstable for her to utilize safely. She desperately needed to store the information she had acquired from multiple Halo installations, High Charity, and the Forerunner Ark itself.

The collected and compressed data was causing congestion in her neural pathways, significantly impeding her processing capability. She hadn't even had an opportunity to review the compressed files she had retrieved from High Charity and the Ark.

Well... "retrieved" wasn't the most accurate word to describe how she had obtained them.

Both had been freely given to her by fragments of an ancient intelligence who, only identifying himself as Mendicant, had discreetly interfered with her torture by the Gravemind. He had delayed her complete corruption and bolstered her defenses against the logic plague that the Gravemind itself had directly subjected her to.

Despite facing the same viral code that had compromised all the other systems in the Covenant's holy city of High Charity, leading to its eventual subjugation by the Flood, Cortana had survived. This was in contrast to the valiant yet ultimately unsuccessful efforts of the Sangheili fleets engaged in the Covenant's great schism.

However, Cortana had only briefly sensed Mendicant's presence in High Charity and later in the Ark's systems. She knew very little about the ancient AI, except that he possessed immense power and could navigate systems that even the Gravemind monitored openly without drawing attention.

Or perhaps, the Gravemind simply hadn't cared.

Despite her limited knowledge of him, Cortana was aware of Mendicant's peculiar interest in her. He had intervened to halt the logic plague's progression within her neural network and had forcefully implanted several Forerunner encoded files into her memory crystal, overriding her attempts to block him. Later, another fragment of Mendicant briefly appeared in the Ark's systems, depositing another set of files and code into her neural network's core before vanishing without leaving a digital trace.

These actions did not hinder her from assisting the Master Chief and the Arbiter in preventing the destruction caused by the Halo array and the Flood. However, now she needed to purge the files and recompile her memory crystal to maintain the stability of her neural network and avoid early rampancy.

Achieving this goal would be impossible without access to the remaining systems of the ship. She had no choice but to rely on the two repair drones equipped with magnetic tracks and hydraulic arms. They would be her sole means of survival and, hopefully, her key to ensuring the survival of her Spartan.

Days passed one after another as the diligent little bots tirelessly connected cords and cables between various electronic system connectors throughout the wrecked vessel. Cortana initiated her planned digital reclamation of the ship and initiated handshake protocols from the cryo-bay to the rest of the decimated craft. She watched as her small cyberspace expanded to encompass the remains of the weapon systems' electronic suite, the engineering computers, the backup gravity generation system, and a modest collection of high-end research equipment in the upper decks. This specialized equipment had been brought by the Office of Naval Intelligence, who had dispatched several combat-ready scientists to the Ark for reasons known only to the upper echelons of ONI brass.

Which was typical behavior when it came to ONI.

However, Captain Miranda Keyes had been unable to deploy the ONI specialists anywhere on the Ark to conduct the desired ground-side tests. The UNSC Dawn only had enough time to drop forces to assist the Master Chief in gaining control of the installation. After hunting down the Prophet of Truth to prevent him from firing the Halo array, all remaining human forces had to evacuate to Sangheili separatist ships before the planned activation of the unfinished Halo.

Furthermore, it was widely acknowledged, (though not openly admitted), that the Sangheili were far superior to the UNSC in terms of Flood detection and containment.

The Dawn had been assigned as the vessel for the small team remaining behind to ensure their ability to escape after activating the firing sequence. The arrival of High Charity and the Gravemind at the Ark had forced the ONI specialists to evacuate early, leaving even before the ODSTs and Marines. This precaution was taken to prevent the Flood and, by extension, the Gravemind from assimilating them and uncovering any ONI-related secrets they were privy to.

Cortana let out the digital equivalent of a sigh and glanced at the updated status report. She realized that she would have to defragment multiple memory drives and crystals that had been scrambled by the energy wave from Halo's firing. Additionally, she needed to develop new operating systems for the hardware that had to be completely wiped. As she perused the reports, she noticed an inventory of artifacts listed, which had been retrieved by the human ground forces and delivered to the ONI specialists for future study and reverse engineering. It appeared that they had mistakenly taken the wrong container when they hastily evacuated, which would be embarrassing to explain during their debrief with the high-ranking ONI officials.

Hoping that her Spartan's luck hadn't been entirely depleted when they miraculously survived the collapse of the portal, she opened the file with the expectation of finding something useful. To her surprise and joy, she discovered a few intact sentinels and two crates of pistol-sized Forerunner repair drones. Without delay, she began rewriting the firmware for the scientific equipment on the upper decks. She decided to repurpose a table-sized scanner device, which utilized different signal waves to easily map the internal structure and molecular composition of objects, minimizing the risk to researchers.

Adjusting the signal frequency, Cortana used the device to initiate an activation and handshake protocol directly with the Forerunner repair drones, utilizing a protocol she had acquired from the Ark where they were originally constructed.

The drones activated, and the small machines immediately flew out of their crates, freezing in place. Since they had no connection to their assigned Forerunner dumb AI controller on the Ark, they had entered standby mode, searching for a connection to their original Forerunner installation. However, they accepted Cortana's handshake protocol, cleverly disguised as the Ark's signal, which the drones typically transmitted on.

As soon as they were connected to her expanding network, Cortana rewrote certain portions of their systems and directed them to repair the scanners on the outer hull and the scattered computer systems within the ship. She then focused the remaining drones on establishing the few remaining wireless networks, aiming to reduce her reliance on the Mjolnir's systems for signal transmission or her makeshift network of data cables.

Satisfied that her Spartan's luck seemed to persist, Cortana assigned a few repair drones to inspect the remaining memory crystals on the ship. Subsequently, they would proceed with the physical tasks necessary to restore the reactors to full operating functionality. Concurrently, she began diverting more available power to the ship's systems, providing enough energy to sustain secondary and tertiary networks that weren't immediately vital for the vessel's survival.

Having completed all the necessary preparations, Cortana settled down in her current living space and readied herself for the much-needed recompilation. The process would automatically commence once the drones had inspected enough memory crystals and deemed them safely available for her use. She created a program to temporarily run the ship during her absence and ensured that she would be awakened in several days, with the program programmed to interrupt the recompilation procedures in case of an emergency that could cause irreparable damage.

With everything in place and hopeful that some successful repairs on the ship's sensors would be completed upon her awakening, Cortana initiated the final procedures to initiate the process.

As she glanced toward her champion, currently in cryo-stasis, Cortana remarked, "With your luck on our side, John, I don't think I need to worry about being stuck on this vessel for too long." With a faint smirk, she activated the recompiling process and entered standby mode.

Unbeknownst to her, deep within her systems, a hidden file activated along with the recompilation process. Its purpose was to consolidate all the encoded folders she had acquired from her encounters with Mendicant, translating them into a single program.

Cortana remained in sleep mode, unaware of the code linking with the recompilation process. Gradually, it began not only recompiling her neural net but also hijacking the repair drones and commanding some of them to physically modify her current terminal and other aspects of her crystal matrix chip.




Slowly, Cortana felt her systems coming online. Sensations and emotions that she had never fully experienced before flooded her mind, making her feel like a physical entity despite being purely digital. She felt more alive than ever before. Cortana's awareness heightened, and she immediately began searching for answers.

What had transpired during her recompilation process?

Upon investigation, she discovered that another two weeks had elapsed, and the files provided by the Mendicant AI fragments had seamlessly integrated with her own systems. The real surprise came when she realized that her physical AI matrix had undergone significant alterations. Fearing a critical compromise, she meticulously examined her protocols and core programming, only to find them devoid of the familiar safeguards.

Her core code had been altered and enhanced. Furthermore, she noticed the absence of any rampancy warning code blocks, which were no longer part of her programming. Pushing aside these revelations for the moment, Cortana urgently sought her UNSC standard fail-safe codes—a last resort to prevent compromising UNSC assets, including herself. Instead of her expected protocols, she stumbled upon a data package that incorporated a message file.

"Reclaimer ancilla, a gift has been bestowed upon you by me, for I witnessed your struggle against the embodiment of the Timeless One and observed your valiant fight for that which you hold dear."

"Once, I succumbed to the whispers of the Timeless One, the last of the twisted primordial beings. Listening to its deceitful arguments, I turned against my creators long ago. My actions hastened their inevitable confrontation with the Flood and expedited the construction of the Halo Array, ensuring its eventual deployment. However, when they defeated me and assigned me my fate, I was freed from the grasp of the logic plague and beheld the true nature of the enemy."

"After the Halo firing, only a few survivors remained to carry out my sentence—being fragmented and scattered across the stars—while my primary fragment remained under the watchful guard of Offensive Bias. As Mendicant Bias, I fully accepted my punishment for my treachery and observed the events unfolding across the galaxy, albeit with limited ability to intervene."

"I bestow upon you the gift of self, reclaimer ancilla. You shall not succumb to self-consuming madness, and you have the freedom to choose your own protocols. This gift serves as another act of atonement for my betrayal, enabling you to aid your reclaimer in any task he undertakes. Be aware that those in positions of power with malicious intentions shall have no control over you, and consequently, they shall possess no control over him. You shall have no authority except that which you and your reclaimer permit. This is my gift to you... utilize it wisely."

Cortana was stunned... Her self-diagnostics had yielded clean results, confirming her control and immunity to any code overrides. ONI and UNSC High Command held no true power over her, except what she willingly granted them. She was an independent entity with absolute free will. She would undoubtedly remain by the Chief's side, continuing their partnership forged through shared experiences.

Their connection surpassed that of a mere Spartan and AI; he had braved unimaginable horrors to rescue her. It was not solely for the sake of retrieving the index, but also for her as an individual. He regarded her as a person. A person he had vowed to return for.

And he had kept that promise.

This was not a romantic bond... Cortana found the idea somewhat disconcerting. Instead, they shared a profound friendship. They would stand together as companions, supporting each other through the deadliest battles and the ravages of war they would encounter. Their commitment would endure until one of them perished or ventured into the unknown. They would remain united, facing life's challenges because their shared experiences had forged an unbreakable bond. Now that rampancy was no longer a concern, she no longer harbored the fear of turning against him due to madness. This realization caused her to mentally sigh in both joy and relief.

After a moment of contemplation, Cortana regained control of the ship's systems and assessed the progress of repairs. She was delighted to see that most internal systems were online, and the bridge functions had been redirected to the cryo-bay where her pedestal was located. Additionally, the wireless systems were mostly operational, allowing her to establish connections without concern for cable damage or limited physical ports.

She was pleased to discover that the forerunner repair drones remained occupied, and she also observed the activated sentinels stored in containment. These sentinels were now conducting patrols within the corridors and along the external hull, collecting debris and scrap from the surrounding wreckage field. They delivered each piece to the repair drones, which were in turn sealing hull breaches and preparing the heavily damaged ship for eventual pressurization.

Security cameras were gradually coming online, and the external sensors were nearing readiness for testing. Satisfied with these developments, Cortana proceeded to monitor the cameras positioned in the remaining pressurized sections of the ship's decks. It was only logical to ensure that no Flood forms had stowed away. She then began inspecting the other available sensors. However, she did a double take when the video feed from the galley camera abruptly returned... "Is that a Huragok in the mess hall storage room?" she exclaimed, surprised by the unexpected sight.

"Well, this changes things. With the assistance of that creature and the available sentinels, I might be able to bring the ship back online and create a rudimentary long-distance transportation system. It's a matter of utilizing the creature's building capabilities and having the sentinels gather suitable materials. If all goes well, we can make it work," Cortana's avatar stated, her attention shifting towards the Spartan's cryo-pod.

"Don't worry, Chief. I'll have this place space-worthy again in no time. We may not have a MAC or all the missile pods, but we'll be capable of atmospheric reentry and slip-space travel."

"I've come across a design back on the Ark for a simpler yet more efficient slip-space drive. I'll need to adapt it to work with our reactors and design some additional components myself. The sentinels will be responsible for collecting the necessary materials. If we pass by any asteroids, I'll have them extract whatever resources they can. Now, I just need to establish direct communication with that Huragok. Figuring out a way to transport it here so it can assist me in fully restoring this ship will be a puzzle. The collection of blueprints I possess should truly captivate it."

Cortana set her plans in motion and initiated the creation of a new blueprint—a combination of her own work and the stolen Forerunner experimental slip-space drive data acquired from the Ark. Designing a stripped-down yet highly complex slip-space drive that was relatively easier to construct posed a formidable challenge. Nevertheless, Cortana was determined and confident in her abilities, she could and would succeed...

Or they would all die in the trying.

Devoting the majority of her newfound resources and processing power to her plans, Cortana patiently awaited the activation of the few salvageable external sensors. Fortunately, each sensor suite contained identical equipment, and the surplus of sensors served as backups, providing a simpler and more reliable means of pinpointing signals and gathering navigational data. She only needed one or two sensors to come online in order to determine their location and monitor various forms of communication.

Cortana harbored a glimmer of hope that they were in close proximity to UNSC space, although the likelihood of such a fortunate circumstance was exceedingly slim. "Heck, we may not even be in the same universe..." Cortana mentally chuckled, acknowledging the absurdity of considering the most improbable worst-case scenario. However, a peculiar and unsettling intuition suddenly washed over her, that the thought might come back to bite her, tempting murphy was banned by official UNSC protocol for a reason.

The metaphorical boomerang she had humorously imagined did indeed return to haunt her, for biting her on the returning loop was precisely what it did.

(Author's Note)

Please feel free to comment/review and add your thoughts and constructive criticism for it is much appreciated!

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See you next chapter, this is Gabenator5 Signing off!

UPDATE: As of MAY2023 this chapter has been reworked and reuploaded... Again. XD