A/N: This went on far, far longer than I anticipated. It wasn't ever meant to be one hundred and one chapters, nor was it meant to have a third sequel, but here we are.
Chapter 1 – Our Normandy
The calm before the storm. As cliché as it was, no better phrase could describe the attitude aboard Admiral Adam Grayson's fleet numbering beyond ten million ships. Most of these vessels were operated by no-nonsense, all-military clones of Athena from Pandora. Such individuals required virtually no relaxation, no entertainment, and none of the civilian-grade comforts that were faithfully digistructed into each Revenant.
"We're not filling the pools" insisted Grayson. "Water's a bit short, even after re-appropriating every last drop from those Republic Intelligence Service fit-out facilities. Also, showers every third day, no more!"
Still unable to store water digitally or generate it via that method without producing a toxic mess, the only remaining source ended up being hydrogen fuel cells, often included as backup power aboard starships. Such water prevented shortages, but didn't allow for luxuries.
Samantha Shepard tried to treat it as shore leave, but such relaxation eluded her as she knew full well her position within the fleet: leading one of several prongs of a massive charge toward her ancestral home—Earth. Mere hours remained before reverting from hyperspace. Hours she'd been told to spend sleeping, but couldn't. Despite going off on Cortana in absentia earlier while speaking to Sarah, she missed the comfort of having an AI around. No EDI, no Cortana… Just a cold, gray starship with several hyper-fast computer cores, but no personality whatsoever. Its monotone "voice" warned her "ten minutes to realspace reversion."
"When did that happen?" she muttered. "Did I get sucked into some kind of time warp?"
Quickly, Shepard threw on her uniform and made fast time to the bridge in time for transition to realspace.
"You know the drill, Shepard" came Admiral Hackett's gravelly voice over the comm. "So do the clones—everyone knows the part they must play if this invasion is to be successful."
"Well, here we go again. One more giant space battle and the ground-pounders might finally have their day!"
Three squadrons of Star Dreadnaughts for a total of eighteen ships appeared first—the "tip of the sword."
"Captain Shepard, sensors are showing…nothing."
"What do you mean?"
"Ma'am, there are no defenses, no ships, no stations… Just a planet covered in Flood biomass. Residual readings suggest there were once large structures in orbit, but they disintegrated years ago. By who or for what purpose, Captain, I cannot tell."
"My guess is the Flood digested them" replied Sam.
So strange to finally have that rank after unofficially holding it for damn near a decade.
Shepard opened her mouth to give the order. The big one. The start to the end. She smiled. This time, she would not be burning defenseless civilians. The fire would cleanse and allow reclaiming of her home.
"This is Captain Shepard on authority of Admiral Hackett: Begin Base Delta Zero."
Ordinarily, destroying the entirety of a planet's crust, atomizing its topsoil, and reducing anything on the surface to molten remnants would not have been necessary or even productive. But with digistruction for repairs and the threat posed by even a single Flood spore remaining untouched, a "BDZ" made perfect sense.
Though naval architects endeavored to avoid unbalanced armaments, it was still the case that Revenant-class Star Dreadnaughts possessed more weaponry on their topsides than bottoms. Each of the eighteen would position itself so its orbit would look "upside-down" as its bridge tower pointed toward the target. Some level of weapon range was recovered despite synthetic Tibanna due to the real deal being mixed in from RISE's arming depots, and the dark energy reactors supplied enough energy to double the power fed to turbolasers.
Triangular bridge windows darkened, polarizing to prevent eye damage from the incredible lightshow going on outside. With over five thousand primary weapons (more than half of them firing down into the planet now) multiplied by the total number of ships, Earth would be declared Flood-free within hours. Even the tens of thousands of smaller weapons which were considered the main armament on a Curator or Minerva added to the blaze of firepower crashing into Earth's yellow-brown surface, further demonstrating the sheer power of Star Dreadnaught designs.
"This is both awe-inspiring and chilling, to wield this much destructive ability" said Shepard to no one in particular as waves of fire washed over Earth.
"Ma'am, we have plenty more of these to conduct" replied a nearby ensign. "There are tens of millions of clusters left to clear!"
The lack of any resistance whatsoever had almost every commander on edge, but Cortana assured them it meant the Flood likely became complacent, so used to nothing of note happening it saw no reason to deploy its monsters. This would ultimately turn out to be wrong, but not for a while.
After the first admittedly-overly-heavy-handed clearing of Earth, ships were divided into more practical groups. Larger systems saw the arrival of a Star Dreadnaught; the rest a squadron or two of Minervas. The four remaining Avengers also saw duty, using their massively enlarged combinations of weapons to great effect. Really, Minervas and their soldiers would be far more useful for dealing with whatever militarized shenanigans took place within the Trans-Galactic Republic's Home Galaxy, not clearing Flood.
At Artemis Tau, the massed guns of Minervas kept Flood at bay. Facing not one but three of the Flood "monster ships" only briefly seen prior to using Farsight to drag Ultimatum away, only a timely intervention saved the fleet. Cortana finally managed to defeat the last rings of security surrounding Ultimatum's remaining Soul Reaper missiles, dialing down one until its detonation would only toast part of a system instead of at least a parsec. Though Minervas would get caught in the blast, it was considered a necessary move and the three Flood superships disintegrated in a blinding flash.
"I hope they don't have too many more of those" sighed Cortana. "We only have nine missiles left."
"They weren't duplicated with the rest of the ship?" asked Grayson.
"No. Would have taken more time—even RISE was adding them afterward, and the arming depots didn't have any aboard. I suspect they were shipped in from yet another facility which made no appearance in any record I parsed when we captured each of these stations."
"I'm putting out a fleetwide call—any force that encounters the Flood supership is to turn tail and run. However, I will be using the cloak-capable vessels we have to tail these beasts so we can at least avoid them."
"What about the Home Galaxy?"
"Cortana, if you think we can split our forces…"
"I'm just warning you that while we focus on one threat another may knife us in the back. The Republic Intelligence Service is not likely to be sitting around playing sabacc while we do the 'hero's work.'"
"How is work on that slipdrive coming?"
"Crews report that the large-scale Odyssey-class drive will be ready to install on Ultimatum within weeks. Unfortunately, it's a choice between much of the ship's spinal-mounted weaponry and the added propulsive speed since preventing temporal issues at those velocities is…problematic."
"Once we have the slipdrive, I'm going to 'phone home' and see what's going on. What about stealth armor?"
"It's not armor, per se. A surface scattering field will drastically reduce any sensor returns from the ship—and any that do come back will be badly garbled. But it's operational. Be warned, however, that significant weapon discharges or ship launches will disrupt the field and allow a cleaner read on Ultimatum."
"It sure is nice to have plans going the way we want for once."
"Agreed. Now, we should get back to work."
The AI's image disappeared, and Grayson resumed coordinating his fleet.