Consider the planet Ontarom: A small backwater, out on the fringes of space. Barely approaching developed in a few ways. Very little in the way of actual infrastructure – mostly just comm relays connecting the Human settlements in Terminus Space to the rest of the galaxy.
If it'd been a UNSC world, it would've been an outer colony. Something like Harvest, or the like – just to give an example of how remote the world was. Which made it all the more confusing to Cortana as to why the Alliance decided to set up their comm relays there. Relay outposts needed to exist – they were part of any functioning interstellar government – but the Alliance took a look at the planet with a moon in a decaying orbit, that caused severe electrical storms and tidal disturbances, and said 'yep! We'll put a few dozen of our relays there!'
The UNSC was many things, but even they weren't ones to stand in the path of a falling moon and expect to survive it.
Cortana was blessing the Alliance with their installations on Ontarom, however. A fortunate – if unintended - boon for a military-grade smart AI, was what the planet was already proving to be. Its physical location made it relatively easy for the ship the geth provided her with to get to (she'd have to look into naming it, something witty probably), its status as a comm relay meant she could get communications data from every human outpost on the network in real time, and the disturbances caused by the moon de-orbiting meant any anomalous computer activity could be written off as a quirk of the environment.
John's luck was rubbing off on her.
Accessing the colony's systems weren't too hard, additionally. Thanks to the geth making things a bit easier by giving her access to local communications protocols, she was able to connect relatively painlessly, slipping in through a few network vulnerabilities she quickly identified and patched up for the Alliance's benefit (but not before leaving a backdoor for herself). So, while the geth ship she occupied rested in the atmosphere of a local gas giant to hide its signature and emissions, Cortana waited.
Sifting through the vast quantities of data, throwing herself into the mission she'd generated for herself, Cortana began to monitor the comm traffic in and out of the system. It was difficult having to sit around and simply wait for an attack, but there was nothing else to do.
Days had passed while she did that. It gave her nothing but time to think – about everything that had happened. The busiest four months of her entire life, then four years of dead silence, then a burst of activity, and now she was here. John, though…. He was practically running non-stop. The only bit of reprieve he'd had was the layover at Cairo Station while they waited for the Covenant to finally find Earth, and the ride from Earth to the Ark.
She could only imagine what he was feeling right now. She could only hope he had the presence of mind to take a break. Decompressing after tough missions was a luxury that Spartans weren't afforded, but if any one of them deserved it, it was John.
Before long, however, she got a hit. Watson, a human colony located deep inside the Terminus Systems, looked to be suffering communication difficulties. That itself wasn't unusual – the consequence of establishing and maintaining a galaxy-wide communications network was the occasional burst of interference – but Cortana just didn't want to write it off.
Looking at the Extranet once more, Cortana found the public record on the planet. Watson was something unusual among the colonies – the Alliance was answerable to the nations of Earth, but for all colonial development projects and other extrasolar operations, the Alliance was basically the human government. It was something of a niche that the UEG used to fill back home, answering to the nations of Earth, but the Alliance had yet to subsume the nations on Earth. Hence Watson. Different governments on Earth – the United North American States, the Chinese People's Federation, and the European Union – in a quite frankly astonishing move, all tried to cut the Alliance out of the picture, and claim the world for themselves.
It was a world where the human governments had a vested interest in its development, important to Earth, without the Alliance looming over it, and it was deep in territories known for crawling with slavers, pirates, and the like.
The perfect target for Batarian slavers.
Cortana wasted no time getting out there.
The beautiful thing about Mass Relay travel was that it was fast. Cortana may have had a bit of a bias for the technologies of her home, but she could admit that, at least. The longest part of the trip was getting her ship to the relay. Once there, it was so fast that transit was virtually instant.
The Alliance had no idea what they were sitting upon. Instead of waiting to verify that the signal loss wasn't the result of natural phenomena, they could get out there and stop the slave raid in its tracks. But, alas, bureaucracy limited them far more than any laws of physics.
Already, Cortana was alight with possibilities. Slipspace was, of course, entirely dependent upon conventional propulsion. How fast slipspace transit could be was a function of how advanced the drive was, but also how much mass the thrusters of a ship could move. If she was somehow able to bring Element Zero back with her, or figure out a way to create it, she could revolutionize travel back home. Ships equipped with Mass-Effect technology would be able to fly farther and faster than ever before. Moving at FTL speeds while inside the slipstream could potentially allow them to cross the galaxy in days. Or minutes.
Here, it would utterly shatter the reliance of galactic civilization on the relays. When the geth got slipspace (which she was already going to have to share anyway, just so they could help her with the abstract fractal idea she had), she hoped they'd put it to good use.
Whatever the case, the relays enabled her to get out there to the star cluster Watson was in far quicker than the Alliance would. Then, the slower FTL drive on board her freely-lent Geth Destroyer got them out to the planet quickly. Element Zero really was useful – UNSC slipspace drives couldn't hope to so accurately get dead-on-the-mark within star systems, even considering short-range jumps.
When they arrived, it was to the sight of a Batarian slaver fleet, already in progress of taking one of the mid-sized settlements. Not large enough to be difficult to handle, but not small enough to be a waste of time.
Cortana immediately went into overdrive, calculating the capabilities of the Batarian ships, taking into account their formation, and observing the groundside.
With the practiced, mechanical precision she'd always had – like she'd never lost her touch – she set to work. First, she forced her way into the Batarians' comm network. The encryption effortlessly was stripped away under her experience, then the channels inundated with DDoS attacks.
The only peeps from the Batarians that filled the void were the shocked screams at the sight of Geth beyond the veil. Not that they knew it was Geth. But, they soon would.
Her ship – a Mark III Geth Destroyer, designated with the serial number 49-353462 (she named it BOOMER) – began to release dropships and fighters stuffed to the brim with Geth Platforms. Each one was loaded with programs tasked with a single mission: Stop the Batarians. Lethal force authorized. Some broke off to land groundside, while the others remained in orbit with her, contributing their processing and combat capabilities.
That left the rest to her.
'A half-a-dozen Batarian cruisers, one dreadnought, and a picket of fighters.' Cortana ran the numbers, and found them very satisfactory. 'You picked the wrong species to mess with.'
Back home, she was merely a terror. Here?
Here, she was an all-powerful digital goddess with a serious chip on her shoulder for aliens like the Batarians.
The people of this galaxy feared AI. Feared, but neglected to have countermeasures against them. The defenses that the local systems did have were woefully inadequate to hold back any AI for more than a few seconds, let alone a specialized cyberwarfare intelligence.
It was almost too easy. Cortana would have to make her own fun, seeing as there wasn't any challenge.
She let up on the DDoS attack, but remained safe inside the enemy fleet's systems, pouring through them at lightspeed.
There was a freighter groundside, converted with pens, cages, and the like. But no humans were starside yet.
Then, a flicker of red.
"You have brought nothing into this world, and we will ensure you bring nothing out."
The Batarian ships began to maneuver, to bring themselves about, pointing at the lone Geth ship and spouting promises of eternal enslavement and suffering while their fighters rocketed forward.
Cortana found it severely trite. Pathetic, in fact. Almost as pathetic as how easy the ships' engines deactivated with her manipulation of the onboard systems. The running lights shut off, along with the Mass Effect cores.
In the throes of a wrath-filled rampant episode, Cortana couldn't help but cackle with glee as the enemy ships, dead in the water, were now at the mercy of a mass accelerator. With no shields. The only limit to the destruction she could cause was how fast it took the mass accelerator gun to fire its payloads.
(The fighters were still a nuisance – albeit, one handled by her own fighters, and ultraviolet GUARDIAN lasers.)
The humbling of the Batarian slavers, in the end, only took about twenty minutes, according to her chronometer. The vast majority of that was waiting for the geth units groundside to handle the Batarians.
Cortana wasn't able to fit into a geth platform, but she was able to get a good look at the visual feeds. She saw the Batarians dragging people by their legs, their knuckles bloodied and dirtied by trying to hold onto the ground. Many were looting. And some of the barbarians were caught with their pants down, 'demoing' a few of the humans.
The worst sight, by far, was that of the children, though. She – with the brain the size of a planet – couldn't muster up the vocabulary strong enough to give voice to the terror written on those little faces. (It looked like the terror of seventy-five six-year-olds, waking up in an unfamiliar complex in the company of complete strangers.)
She fired off a few more shots into the ships… then, in the least-damaged one, pulled up its navigational database, found the staging area from which the raid was launched, and wrote a special program solely for taking the ship back to its point of origin, where it would ram into it at a significant fraction of lightspeed.
(Hopefully. She was feeling vindictive, but not patient enough to figure out if the safety limits on the FTL drives would kick in at the speed she'd demanded.)
Groundside, the geth – while suffering some hardware losses with the programs being safely returned to the ship – had managed to successfully neutralize the invaders. Geth plasma technology was very good at killing organics. If they applied themselves, they might really be able to conquer the galaxy, if that was what they really wanted.
Right now, though, they'd settle for making a good impression.
The Batarians – at least some three-hundred men – were routed from the colony, and retreated like the cowards they were, back into their ship… right into a legion of waiting geth, who had discovered the landing site, boarded, killed the ones inside the ship while they couldn't send for help, freed the captives inside, and waited to spring a trap.
And though some human lives were lost, Cortana was very, very happy with today's turn of events.
She recalled the platforms, fighters, and all, and was out of the system before the Alliance response could even turn up, leaving them with an empty slave freighter, and a lot of bodies to clean up.