Mass Effect: Trailblazer

A Mass Effect/Halo Crossover by TallYapflip

Prologue: Energy

September 21, 2531

Aboard the UNSC Trailblazer

"Captain, ONI survey probes reported strange sensor readings from a nearby star cluster before going dark." The Sensors Officer declared, reading over the data from the recent mission update. "FLEETCOM Alpha wants us to investigate."

"What kind of sensor readings?" Captain Sypkin asked, making his way over from the center of the bridge, towards the front observation window.

"Preliminary data suggest Dark Energy, Captain." Henry, the AI attached to the Trailblazer, explained. "Data from the probes indicate that this phenomenon is contained to a radius no greater than three kilometers. It's highly concentrated."

"ETA on our arrival?" Sypkin asked, looking to the AI's holographic image.

"System is just over nine light years out, sir." Navigation reported. "Just under two days."

"Navigation, set a course for the edge of this system, follow all standard operating procedures." Sypkin ordered. "Spool up the drive."

"Right away." Navigation responded.

Sypkin watched as the crew prepared for a standard Slipspace jump. The ship began moving on a vector that matched the rough location of the nearby star system, designated as "SH-224" on UNSC Star Charts.

"Spooling up the Slipspace drive." Navigation declared. "Diverting power from non-critical systems to engines."

Sypkin watched as the rift into the Slipstream was torn before the vessel. The gaping, swirling maw of energy lapped hungrily at the surrounding space, fighting the forces that had torn it open. In an instant, the space surrounding the Halberd-Class Destroyer shifted to complete blackness. The ship had successfully jumped into the Slipstream, just as it had dozens of times before.


September 23, 2531

Bridge of the UNSC Trailblazer, SH-224 System

"Bringing us out of the Slipstream." Navigation reported.

Captain Sypkin stood behind the consoles showing the rough data about this system. It housed a single star, not unlike Sol, as well as six planets. Most were scarcely more than balls of uninhabitable rock or gas, but one laid in the habitable zone of the star. If they were lucky, this system could house a colony one day. Then, orbiting one of the gas giants, there was the Dark Energy signature. It was so miniscule compared to the planet that it could have easily evaded long-range scans from normal sensor equipment. It was no wonder that it took an ONI survey probe to actually detect it.

Sypkin glanced up from the console he was locked in a staring contest with. The small, white blip in the distance soon became an exit point from the Slipstream. An instant later, the vessel slipped back into the observable realm, sitting a few million kilometers away from the nearest planet, a small planetoid not unlike Pluto. "Launch high-intensity scans into the surrounding space and update FLEETCOM Alpha on our arrival. Send any relevant information we find to Admiral Cole."

"Right away." Sensors acknowledged.

Sypkin watched as the sensor data rolled in. Most of it was benign planetary data; atmosphere compositions, surface area, and all that. What truly caught his eye was the presence of multiple Dark Energy signatures, all converged around the potentially-habitable world. As the data about this world rolled in, he could tell that it was no longer potentially-habitable, it was habitable. Oxygen-Nitrogen atmosphere, minimal carbon dioxide, strong magnetosphere, all of the ingredients for colonization.

"Captain…" Sensors asked, catching his attention as the data continued to roll along the console. "You need to look at this."

"What is it?" Sypkin asked, walking to the Sensors station, Henry popping up on a nearby holographic pedestal.

"We're detecting two dozen signatures around the garden world…" The sensors officer explained, pointing to a visual depiction on the console's interface. "Temperatures in the millions, centigrade. They're arranged in what appears to be a holding pattern around the planet. They're maintaining a geosynchronous orbit."

The implications of that simple statement hit Sypkin like a truck. "Starship thrusters…" He mumbled, looking at the readout intensely. There was nothing else it could be. No natural phenomenon in the known universe could arrange heat reactions like this in such a perfect military holding pattern. "By God…" He muttered. "Did we just make first contact?"

"It appears so…" Henry spoke up, his voice remaining level and calm. "I am detecting an incoming laser detection scan. Whatever they are, they know we're here."

"Send the information to FLEETCOM immediately!" Sypkin ordered. "Bring the ship to alert status."

"Slipspace comm sent, arrival in twenty minutes." Henry said. In an instant, he turned to face Sypkin. "Captain, I am detecting a gravitational anomaly twenty thousand kilometers off of our bow!"

Before the Captain could register what the AI had just told him, a vessel appeared before the observation deck, followed by six others of similar make. The forward vessel appeared to be just a bit smaller than the Trailblazer, while the others were about half the size of the destroyer. "Oh my God…" Sypkin muttered, looking out at the vessels before him.

The entire bridge had fallen silent as the crew looked on in wonder. They had just made first contact with an alien race. "Sir…" Sensors reported, glancing back over to her console. "We're detecting a more in-depth scan."

"Henry, attempt to communicate." Sypkin ordered. "Dig the First Contact Packet out and send it over all frequencies."

"Right away." Henry responded.

Sypkin continued to stare out in wonder, but his gaze was interrupted by the Sensors station calling out, panic seeping through her words. "Captain, vessels are diverting power! They're charging weapons!"

Sypkin's heart sank into his stomach. This wasn't how he hoped First Contact would go, but he knew protocol. "Charge forward MAC, fire all ARCHER missiles!"

The last thing the Captain saw was a hypervelocity slug spearing through the observation window. In an instant, the Trailblazer went up in flames as the internal missile magazines racked detonations across the decks, eventually culminating in the ship's reactor core destabilizing. In a few thousand years, the explosion would be visible from Earth, nothing more than a tiny blip against the star-lit sky.


October 17, 2531

Bridge of the Valiant-Class UNSC Everest, Command Cruiser of Battle Group X-Ray

"Admiral, we'll be exiting the Slipstream in five minutes." Navigation Station declared.

"Battle Group X-Ray reports all hands at Combat Alert Alpha" Communications declared.

"Once we exit, divert all non-essential power to weapons systems and propulsion." Admiral Cole ordered. "Relay the general order to regroup on our flank once we reach SH-224."

"Right away."

Cole allowed himself to drift into his thoughts as he stared into the console before him. The Trailblazer had gone dark, just like the ONI survey probe. The single message that the vessel's captain had managed to send back to FLEETCOM had given concrete proof of what mankind had been searching for: sentient life.

After receiving no confirmation of peaceful first contact from the Trailblazer, HIGHCOM ordered the mobilization of the Navy and the formation of Battle Group X-Ray, a massive fleet of 70 combat vessels. Fifty of these were frigates and destroyers of varying classes, mostly Paris-Classes and Halberd-Classes. The capital-class vessels in the fleet, which totaled out to eight Halcyon-Class Light Cruisers, four Marathon-Class Heavy Cruisers, two Valiant-Class Super-Heavy Cruisers, three Poseidon-Class Light Carriers, two refit Phoenix-Class Colony Ships outfitted for combat, and the centerpiece for the fleet: the UNSC Punic, one of the largest vessels ever constructed. The Punic was a relatively new class of warship, designated as a supercarrier by the navy. It stretched just over four kilometers in length and carried as many fighters as the entirety of the Halcyon-class group. Heading this battle group was the Everest.

Thousands of potential strategies danced around in Cole's mind. Potential flanking maneuvers around the gas giant, covering fighter screens with fire support from the Phoenix-classes, potential boarding operations, and even the possibility of nuclear deployment.

"Admiral, we're leaving the Slipstream now!" Navigation declared.

Cole turned to look as the SH-224 system came into view. The fleet had emerged just under a million kilometers from the system's largest gas giant, with the Garden World directly off their bow. The distant world was little more than a dot in the distance, but it was visible. "Sir, we're detecting scanning arrays!"

"All ships, this is Admiral Cole." Cole said into his personal communications console that he often used to address fleets. "Establish a defensive phalanx in front of the Phoenix-classes. Charge forward MACs and begin closing the distance."

Cole watched as the seventy "acknowledged" pings danced across his command console. "Admiral, firing solutions prepared." Weapons Station declared. "Ready to fire on your mark."

"All ships, fire at will!" Cole ordered.

The Everest shuddered slightly as the twin MAC cannons propelled their ferrous-tungsten slugs at 30,000 kilometers per second, appearing as little more than streaks of white against the black backdrop of space. Dozens of these projectiles streaked towards the planet's defenders, along with hundreds of ARCHER missiles. The First Contact War had begun.


October 17, 2157 (Council Date)

Bridge of the PFS Phalanx, Flagship of the Aephus Defense Fleet

"General Arterius, sir!" Desolas waved his Commander's salute off as he stepped onto the bridge of his command ship, the largest dreadnought in the Turian fleet.

"What do we have?" Desolas asked, walking over to the central command terminal.

"We've confirmed the presence of artificial intelligence aboard the vessel we destroyed, along with nuclear arms." Commander Titus reported. "Hierarchy agrees, you made the right call."

"Did I?" He asked, gesturing to the holographic image before him. It depicted the anatomy of an alien not unlike an Asari, even mirroring the organ functions almost perfectly. There were quite literally three differences: skin tone, gender dichotomy, and the presence of fiber hair in the place of a fringe. "These creatures could have been peaceful… I gave the order when the report of AI Heuristics came through."

"Their AI was attempting to breach our firewalls." Titus consoled. "You acted in the security of the Hierarchy."

"How secure will the Hierarchy be if… when these aliens retaliate?" Desolas asked. "We know little about their capabilities. Everything aboard that vessel, save a few bodies and deactivated electronics, was destroyed."

"The absence of Element Zero in their ships is troubling…" Titus continued on that train of thought. "It's possible that their method of FTL is slower?"

"Given that they haven't responded yet, that's quite likely." Desolas agreed. "We've had time to shore up our defenses here… has the Hierarchy reported this contact to the Council?"

"Not yet." Titus answered. "We're awaiting confirmation from Palaven on whether or not we've breached the security protocols in their probe."

"General, we're detecting more of those rifts!" The female Turian sitting at the sensors station shouted. "Twenty million kilometers out!"

"How many?" Desolas asked, wheeling around to face the forward viewport.

"Seventy." The Sensors operator reported.

"Spirits…" Desolas muttered. "What's their fleet composition?"

"Sensors indicate fifty-two vessels at cruiser weight, seventeen at Dreadnought weight and… one larger than any we've ever seen." Sensors continued. "Length estimates put it at four thousand one hundred and twelve meters."

"By the Spirits, that shouldn't be possible…" Desolas walked over to confirm this. What he saw not only confirmed it, but it terrified him. Hundreds of smaller engine signatures were funneling out of the massive super-dreadnought, likely fighters. "Begin closing the distance and attempt a hail!"

"Sending the request now!" The comms officer reported.

"General, we're detecting massive energy spikes in the larger vessels!" The Sensors officer declared.

"Begin evasive maneuvers! Fire all forward batteries!" Desolas ordered. "Launch all fighters!"

Desolas watched the fifty vessels of the defense fleet return fire with their own mass drivers. The hypervelocity slugs soared in the direction of the incoming fleet. A few moments later, Desolas watched massive streaks of white zip past his vessel, undoubtedly the aliens' first volley. A momentary feeling of relief was soon replaced with dread as the slugs struck true against the shipyard orbiting the planet. Eight of the rounds impacted on the broad side of the orbital shipyard, flaring up in a brilliant flash as several megatons of energy were transferred instantly. The shipyard, in an instant, was reduced to rubble.

One of the cruisers on his port-side flank was struck by an incoming slug, striking against the bow armor. The metal projectile speared through the kinetic barriers in an instant, penetrating clean through the armor and exiting through the stern of the vessel. Desolas' heart sank into his stomach as he watched a single round obliterate a heavy cruiser with little issue, then continue on past the planet unfazed.

"Prepare for a short-range FTL jump, bring us within five hundred thousand klicks." Desolas ordered.


Bridge of the UNSC Everest

"Twelve confirmed hits, Admiral." Weapons Station reported. "Four hostile contacts and one orbital construct destroyed."

"Enemies jumping to light-speed!" Sensors reported. "Gravitational anomalies on our flanks."

"Bring the frigates and destroyers about, engage them once they're out of FTL." Cole ordered. "Prepare ARCHER pods, activate Point-Defense."

"Done." Weapons reported.

Cole watched as the hostile fleet appeared out of FTL on the battle group's port and starboard flanks, just as intended. "Hostile flagship firing missiles on the Punic!"

"Redirect starboard Point-Defense." Cole calmly ordered. "Direct ARCHERs on their engines and weapons hardpoints."

"Hostile fighters converging on the Tempest, overwhelming autocannons." His AI, Sara, declared. "Re-directing SABRE wings to assist."

"Sir, autocannon fire is ineffective, hostiles have some form of shielding." Weapons declared.

"Fire SHIVA warhead on the hostile flagship, conceal it in an ARCHER swarm." Cole ordered.

"Nuke away!" Weapons declared over the cacophony of voices on the bridge. After a moment, the report on the missile's effectiveness was reported. "Good hit, minimal damage to armor, but shields were overloaded. Autocannons firing for effect."

"Focus engines." Cole ordered. "Order the fleet to limit fire on hostile flagship, we're boarding it."

"Right away." Sara responded.

"Four Paris-Classes reporting multiple hull breaches and catastrophic engine failure!" Comms reported.

Cole bit back a curse. These aliens were certainly aggressive, that much had been confirmed by First Contact. He never would have imagined them closing the distance on a numerically-superior force. "Hostile force?"

"Steadily taking casualties, reduced to twenty six active combatant vessels." Sensors reported.

"Admiral!" Engineering called out. "Engine three reports heavy damage, we've lost it."

"Maintain vector." Cole calmly stated. "Roll the ship eight degrees to minimize engine damage."

"Firing RCS thrusters!" Navigation ordered. "Bringing dorsal weapons systems online."

Cole watched as the battle continued to rage on. The Frigates in the fleet were getting hammered by the hostile fleet and sustaining heavy losses, but the capital ships were faring rather well all things considered. Even while being flanked and lacking the shield tech of these aliens, Battle Group X-Ray was taking minimal casualties. The meters-thick armor of the Everest was more than capable of mitigating any damage from the alien missiles or mass accelerators.

After twenty minutes of intense knife-fighting between the two fleets, the UNSC fleet had reduced the alien fleet to ruin, while sustaining fifteen frigate casualties, eight destroyer casualties, a crippled Halcyon, slight damage to a Marathon's starboard plating, and minor damage to the Everest's engines. The largest of the alien vessels, measuring in at just over a kilometer, had been utterly devastated when the destroyers had managed to fire off a MAC. One of the two larger vessels had been completely split in half by the impacting slug, while the other drifted with no engine power and all of its weapons disabled. UNSC Fighters had proven far faster, but lacking the maneuverability than the alien counterparts, taking some heavy casualties in the initial stages of the engagement, but later compensating.

"Spirit of Fire, this is Admiral Cole." Cole began, keying a secure channel to Captain Cutter. "Dispatch five platoons of Marines and SPARTAN Red Team for a boarding operation of the hostile command ship, full pressure gear."

"Yes, sir." Cutter answered.


Bridge of the PFS Phalanx

"Report!" Desolas ordered, watching the blocky, grey ships drift past his own. They had seemingly crippled his ship intentionally. They were left with no engines, no operational weapons, and a rapidly-deteriorating power situation. The normally warm lights of the bridge were replaced by the sickly red emergency lights as the ship's VI automatically adjusted power to the life support and artificial gravity systems.

"Deck 13 has had its hull plating stripped, Mass Effect field generators are down!" The engineering station reported, a heavy crack present on the side of her carapace after being thrown about from the nuclear impact. "Sensors are down, we're drifting and blind."

"Damn it…"

"General!" A Platoon Leader from Deck 13 came over the ship's internal communications network, his voice reverberating throughout the bridge. "Hostile boarding action!"

"Hold them back!" Desolas ordered. "Fireteam Crux is en-route to assist."

"Copy that, General." Desolas could swear that he heard the sound of combustion ballistic weapons over the communicator, but he shoved that aside. His mind had to be playing tricks on him. "We'll hold- Spirits, what is that?!"

"Lieutenant?" Desolas asked, only to be met with static.

"General, we're detecting unknown bio signatures on Decks 13, 12, 9, and 5." The Sensors station barked.

"Damnit… they've already pushed in!" Desolas shouted, walking over to the arms locker by the airlock. He pulled a Phaeston assault rifle from the rack, slapping a thermal clip into the side. "General quarters, all hands, hold your positions! We have hostiles on board!"

Desolas watched as his bridge crew scrambled into defensible positions across the cavernous CIC. The few soldiers among the sailors took up positions near the bulkheads, their rifles propped up against inert computer consoles. Desolas took up position behind his command console, watching the right-most bulkhead.

After a few minutes of eerie silence, the distinct sounds of explosions could be heard throughout the deck. His communicator lit up with updates on the alien positions before being swiftly silenced by gunfire. The longer he listened, the more sure he was. These aliens were using firearms. In an instant, the deck went silent.

"Fireteams, report!" Desolas ordered, only to be met with silence.

In an instant, the two bulkheads leading into the CIC exploded inwards, scattering shrapnel throughout the deck. Two of the Turian Marines near the front of the defenses were peppered by large, sharpened metal shrapnel. Both were eviscerated by the sheer force of the flying metal.

Dozens of Phaeston rifles lit up the bulkheads, their tiny projectiles ricocheting off of reinforced plating, sending sparks flying in all directions. A small group of six of the aliens were shredded by the incoming fire, four in the left bulkhead, two in the right. Their armored bodies clattered to the floor, along with their weapons. He heard a voice call out in a guttural, alien language. It almost sounded as if the voice was being projected through a speaker. Desolas couldn't even dream to understand the language, it was so foreign to him. It simply sounded like gibberish.

"Marines, port side flank! Red Team, starboard flank." The voice barked out. "Prep stun grenades, insert on my mark. Three… two… one… mark!"

Desolas saw four small cylindrical objects clatter to the floor, bounding off of walls. "Grenade!" He shouted, ducking behind the console. A blinding flash of white light and a deafening roar overtook the room. Soldiers and sailors shouted out in confusion, their vision overtaken by white and their ears ringing.

Desolas shook his head, hoping to clear his vision and remove the ringing in his ears. As his auditory senses slowly returned, he heard the sounds of pained screaming, the steady staccato of automatic gunfire, and the sounds of metal meeting flesh. As he popped out from cover to open fire, a heavy metal gauntlet wrapped around his neck in a vice grip. His eyes widened as he found himself face-to-face with a reflective gold visor.

He didn't manage to get a good look at the armored creature before it sent a fist into his carapace, his vision fading to black a moment later.


Bridge of the UNSC Everest

"Casualty report?" Cole asked, hearing the "Mission Complete" ping from Red Team.

"Red Team suffered no casualties, Admiral." SPARTAN Jerome responded, curtly. "Forty eight Marine casualties in the boarding operation, potential hostile HVT secured."

"Potential HVT?" Cole asked.

"Gold markings on the armored collar." Jerome responded. "Appear to denote rank, possible captain or admiral."

"Copy that, Red Team." Cole returned. "Is the hostile vessel secured?"

"Alpha and Bravo platoons are sweeping the ship's lower decks for survivors." Jerome answered. "Further orders?"

"Hold position on the bridge, report in once the vessel is secured and ONI Section One personnel will come aboard."

"Copy, Red Team out." Jerome cut the communication.

"Admiral, HIGHCOM acknowledges our communication." Sara popped up on the holographic pedestal beside Cole. "Reinforcements are en-route from Reach, ETA: three weeks. Our standing orders are to secure the system, blockade the alien world, and await further direction."

"Relay the order to the fleet." Cole commanded. "Dispatch Marathon Group Alpha to the world and destroy any artificial satellites. Launch planetary scans and report any intelligence directly to the Everest."

"Understood." Sara acknowledged.

"Any idea what this is?" Cole gestured to the scan results. They had scanned the source of the dark energy signature. It was a strange, three kilometer-long object shaped vaguely like a teardrop tuning fork. It had a pair of central rings that rapidly rotated around a mass of blue light.

"Preliminary data suggests that it is a method of FTL travel, utilizing an unknown element to propel ships while simultaneously lowering their mass." Sara explained. "This warrants further study."

"Agreed… dispatch Halcyon Group Echo to defend against possible counter-attack. Position them at regular intervals around the device."

"Understood, Admiral." Sara responded.


After thinking long and hard about publishing this, I've decided to go through with it. A few people have asked me to do a direct Halo/ME Crossover for quite some time now, and I've had this idea floating around in my head for the better part of six months or so.

This story will be taking the place of one other that's currently being written. This isn't to say that it'll be abandoned. Rather, I'll be re-writing To Last a Thousand Years to better fit with the idea I have for it (Basically, I'm re-writing the entire alternate history, which will take time.) So basically, expect this to take the place of that one for the next little while.

Time for a bit of outside worldbuilding on this fic. Basically, there were never any Prothean Ruins on Mars. The UNSC formed, and followed the Halo timeline up until the supposed beginning of the Human-Covenant War, which also has not happened. The UNSC has been able to expand and grow to their Golden-Age height, completely unaware of the Council or other alien life until now. The Forerunners still exist, and the UNSC is well-aware of this fact. In other words, the UNSC has no fancy reverse-engineered energy shields or plasma weaponry. Their ships are still relatively slow (compared to Covenant Slipspace drives, and especially the Mass Relays), but much of their space lies outside the Relay Network.

Now that that's out of the way, I hope you all enjoyed the relatively short prologue to this new story. Let me know what you think, I appreciate every review that comes my way, and I do my best to answer them at the end of every update (if applicable).