Author's Note: In Mass Effect, the names of alien species usually begin with a lowercase letter (e.g. asari, turian, quarian, etc.), whereas in Star Trek, they're usually capitalized (Klingon, Bajoran, Cardassian, and so on). My theory is that this because Star Trek species are usually named after their homeworlds (e.g. Cardassians from Cardassia), but in Mass Effect, they're usually not (as in turians from Palaven). However, I also think that each character would think according to the norms of their own universe. Therefore, all species names will be capitalized in the POV of Star Trek characters, and lowercase in the POV of Mass Effect characters.


Chapter 2: To Talk of Many Things

Deep Space Nine's conference room was probably twice the size of Normandy's war room, and far more open. A place for discussion and negotiation, not strategizing; for building peace, not waging war. Shepard appreciated what that said about the Federation's values. Captain Sisko had told her a little bit about the history of this region of space, about the tensions between the bajorans and the cardassians that Starfleet had come to mediate, and she was impressed by the peaceful, cosmopolitan atmosphere of the station. It felt more like the Citadel than any Alliance border outpost.

Both Shepard's squad and Sisko's senior officers fit comfortably around the large table, and everyone seemed to have found their counterpart from the other crew. Doctors Chakwas and Bashir, finally able to converse outside of an emergency situation, were already comparing notes. So too were Liara and Dax—who, Shepard had learned, was not human at all, and far older than she looked. Chief O'Brien had seemed a little taken aback at Tali's face mask at first, but had quickly warmed up to her, and the two were engaged in animated conversation. Garrus had taken a seat beside Worf and was trying—and failing—to strike up a conversation with the perpetually scowling klingon. Ashley and the bajoran, Kira, seemed to have found some common ground, and no one seemed bothered by the presence of an unshackled AI in the room.

Well, Shepard had caught O'Brien and Bashir whispering to each other while trying not to stare at EDI, but she somehow suspected it wasn't her intelligence they were discussing.

"All right, everyone, let's get started," Sisko said, and the room quieted immediately. He let the silence settle for a moment, then addressed his own crew. "Some of us have found ourselves the… guests… of what we've come to call the Mirror Universe in the past," he began. "Now we're on the opposite end of that. There's no way to sugarcoat this, people: Commander Shepard and the crew of the Normandy come from an alternate reality and some two hundred years in the past. Our task is to help them find their way home. I expect you and your departments to render whatever assistance you can."

O'Brien frowned. "Any assistance, sir?" he asked.

Sisko raised an eyebrow at him. "What's your concern, Chief?"

Glancing around at the Normandy crew, O'Brien held up his hands. "Don't get me wrong, I'm happy to help wherever I can." He turned his eyes back to his captain. "I'm just wondering at what point the Prime Directive applies here."

Sisko looked as if the thought had already occurred to him—and he'd noped nobody would think to ask. He brought a fist to his mouth, frowned, then raised one finger. "That… is a very good question, Chief. Use your best judgement for now, and I'll get back to you on that."

Shepard could see her own curiosity reflected on her squad's faces. "The Prime Directive, sir?" she asked.

Sisko sighed. "Starfleet's General Order One. To put it succinctly, strictly prohibits interfering in the development of other cultures—or timelines—particularly by sharing advanced technology. It's the Federation's highest principle, that we're expected to uphold at all costs."

"A law like that could have saved our galaxy a lot of grief," Garrus commented.

"Yeah," said James dubiously, folding his arms. "Or we'd've been overrun by rachni a thousand years ago."

Dax leaned forward, folding her hands on the table. "But you can see where this situation leaves it open to interpretation."

And could complicate things tremendously. "I do," Shepard replied. "We'll try not to stick our noses where they don't belong." To her own crew, she added, "And if any of Captain Sisko's people invoke this Prime Directive with any of you, you're to drop the subject immediately. Is that clear?"

A decidedly disappointed chorus of "Yes, ma'am"s and "Understood, Commander"s was the response.

"And that goes both ways," Sisko said firmly. "Any sharing of new technology is strictly prohibited unless specifically authorized by your respective commanding officer. Does that work for you, Commander?" he asked Shepard.

"Makes sense to me, sir," she agreed.

In all honesty, she was skeptical. But if this was going to work, she and Sisko needed to present a united front to their crews. They could hash out their differences in private. In the meantime, best to err on the side of caution.

"Good." The captain looked down at the datapad in his hand. "All right, people, Commander Shepard and I have put together a list of duty assignments. Chief, you'll report to Lieutenant Gregory Adams on the Normandy with as many people as you can spare to assist with repairs to the engines and hull. Mr. Vakarian and Miss Tali'Zorah will go with you."

"Aye, sir."

"Mr. Worf, you're with EDI and Flight Lieutenant Moreau. Find a way to patch their communications systems to ours so we can talk to one another."

"Aye, sir."

"Dax, you'll be working with Dr. T'Soni to figure out how this happened, and find a way to reverse it. Set up whatever you need in the science lab."

"Aye, sir."

"Major, I need you to set up temporary quarters for our guests. See Lieutenant Commander Williams for anything you need."

"Aye, sir."

"Everyone else, make yourself useful however you can. Any questions?" Sisko made eye contact with each person, and none responded. "All right, then, you have your assignments. Let's get these people home. Dismissed!"

As the newly combined crew filed out of the room, Sisko turned to Shepard. "If you'll meet me in my office, Commander, there are a few things I'd like to discuss with you in private."

"Of course, sir," she said. "Lead the way."


Sisko grabbed the baseball of his desk on his way around it, tossing it into the air and catching it as he dropped into his chair. He chuckled lightly as he looked up at Shepard, standing at a stiff parade rest just inside the door. "Relax, Commander," he said. "Have a seat. I don't want to stand on ceremony with you. Can I get you something to drink? Coffee, maybe?" He wondered belatedly if they even had coffee in her reality.

But as she pulled up a chair, Shepard gave him a smile that was equal parts grateful and weary. "Coffee sounds wonderful, Captain. Thank you."

Sisko turned to the replicator. "Two raktajinos, black." Two mugs of piping hot coffee materialized on the pad, and Sisko couldn't help but grin as he handed one to his astonished guest.

"Uh… th-thank you," Shepard stammered. She studied the mug in her hands as though uncertain if it was actually real. "'Any sufficient;y advanced technology is indistinguishable from magic,'" she quoted softly to herself.

Sisko raised his eyebrows. "Arthur C. Clarke," he replied, earning a look of equal surprise from Shepard. "It seems our two universes share a fair amount of history. Or at least, our Earths do."

"Apparently." Shepard sipped her coffee cautiously, then nodded in approval. "That's delicious. What did you say it was called?"

"Raktajino. It's Klingon, actually. These Cardassian replicators have never been able to get Earth coffee right."

Shepard laughed at that. "Hell, it can be hard enough to get Earth coffee right without a… a replicator." She shook her head. "Klingon… that's Lieutenant Commander Worf's people, right?"

"That's right." Sisko took a sip of his own coffee, allowing the warmth and sheer normalcy of it to take the edge off this truly bizarre situation. "You've met a lot of new species today, haven't you?"

"No kidding," said Shepard. "There's no such thing as Klingons in my… my reality. Or Bajorans, or Cardassians, or Trill. I wonder where our universes diverged, that Earth would be so similar and the rest of the galaxy so completely different."

"Well, in this reality, there are no Turians, Quarians, or Asari. And no Reapers, either." Sisko set down his mug and leaned back in his chair. "Tell me about this Reaper War."

Shepard closed her eyes and let out a long breath—and then launched into a story that made Sisko's blood run cold. She told him about Saren, Sovereign, and the Geth, her own death and resurrection, Cerberus and the Collectors. She recounted the invasion of Earth by giant sentient starships hell-bent on destruction, the battles for Palaven and Tuchanka, the coup attempt on the Citadel, the retaking of Rannoch and the crushing defeat at Thessia. She told him about the people she'd lost along the way: Kaidan Alenko, Mordin Solus, Thane Krios, and the many crewmen of the first Normandy. But most unsettling were her descriptions of the abominations the Reapers made of those they conquered: Husks, Cannibals, Marauders, Brutes, Banshees, and countless other unspeakable horrors. All of the peoples of her galaxy were embroiled in a desperate, seemingly hopeless battle for their very existence. It made the looming threat of war with the Dominion look like a spitball fight by comparison.

Sisko found himself looking at her in a whole new light. She couldn't have been much older than thirty: young even to hold the rank of commander, and yet here she was, saddled with more responsibility than most fleet admirals, in the midst of a war straight out of the midst of some Lovecraftian nightmare. And now, finding herself in a universe that had never heard the call of Cthulhu, all she wanted was to go back.

"It's probably arrogant of me to say I'm the only one who can complete my mission," she murmured, staring absently into her now-empty mug, "but… I'm probably the only one who will." She looked up at him again, and seemed to shake herself out of her reverie. "Captain, I can't thank you enough for all of your help. I don't know how to begin to repay you."

"There's no need," Sisko replied, waving off her concern. "We're more than happy to do whatever we can."

"Whatever you can." Shepard toyed with the mug for a moment, then took a deep breath and leaned forward. "About that. I'd like to know more about this Prime Directive."

Sisko blew out a long breath. "That's a bigger question than you know, Commander." He stood and began to pace back and forth, gesturing with the baseball as he spoke. "At its heart, the Prime Directive is a doctrine of non-interference. It was designed to govern contact with less developed civilizations. The simple interpretation draws the line at the development of faster-than-light travel."

"I take it it's not always that simple," Shepard remarked.

Sisko chuckled. "Almost never." He tossed the baseball a few more times as he considered his next words. "Starfleet's primary mission is exploration and discovery: 'to explore strange new worlds, to seek out new life and new civilizations, to boldly go where no one has gone before.' The Prime Directive aims to keep us from unduly influencing the natural development of those civilizations. The trouble is, the degree to which it applies in any given situation is a matter of interpretation."

"I see." Shepard's eyes narrowed, and there was a distinct chill in her voice. "And in this situation?"

"There are a number of ways I could look at this," said Sisko with a sigh. "From a purely legal standpoint, you technically contacted us first, and asked for our help. That alone allows me to suspend the Prime Directive far enough to help you repair your ship and care for your wounded."

"It would be a pretty inhumane law that didn't," Shepard snapped, folding her arms. "I can't imagine not being allowed to help someone who showed up shipwrecked on my doorstep."

"Exactly," replied Sisko, meeting her sudden hostility with outward calm. Damn it, if their crews were going to work together, they needed to be on the same page here. "It's supposed to be an ethical injunction. But the temptation to play God can be… powerful. The Prime Directive aims to curb that temptation."

Shepard still looked skeptical. "You said it only applies to pre-FTL civilizations, though. We have FTL travel. So what's the problem?"

She still didn't understand. Sisko stopped for a moment as he tried to figure out how to explain it, and then his gaze fell on the replicator in the wall. A simple, everyday thing for him, it had left her utterly astonished. He turned back to her and gestured with the ball. "Magic."

"Magic," Shepard repeated dryly. For a moment, Sisko could have sworn a faint scar on her cheek glowed dimly red. "You mean in Clarke's sense." She gritted her teeth. "Well, I think that's damned condescending, if you ask me."

Sisko sat down and folded his hands over the baseball. "Look, answer me this, Commander: what did Mr. Vakarian mean when he said a law like the Prime Directive could have spared your galaxy 'a lot of grief'?"

"That's not…" At Sisko's raised eyebrow, Shepard bit back her objections and sighed. "A few thousand years ago, a species called the Rachni invaded Council space. They were ruthless, relentless, threatening everything the Council races had built. So the Salarians took it upon themselves to find reinforcements. They provided another race, the Krogan, with the knowledge and technology to join the galactic community in return for helping in the fight against the Rachni.

"With the help of the Krogan, the Council races beat back the Rachni, and all but wiped them out. But Krogan society is centered on war and fighting, and they reproduced rapidly. They petitioned the Council for more colony worlds as their population exploded in peacetime, and when the Council refused, they rebelled. The Council races couldn't fight them, not so soon after the Rachni Wars, so the Salarians stepped in again. They created a virus called the genophage, that reduced the viability of Krogan young to a tiny fraction of what it had been. The Turians deployed it on the Krogan homeworld, Tuchanka, which put an end to the Krogan Rebellions." She shrugged. "Not saying any of it was right. But I'm inclined to agree with James: without the Salarians' interference in Krogan society, the Rachni would've overrun the galaxy millennia ago."

"Genocide? Biological weapons?" Sisko shook his head in disbelief. "In this reality, Commander, we call those war crimes."

Shepard glared at him, and yes, her scars were definitely glowing. Even her eyes gleamed faintly red. "Listen to me, Captain," she bit out. "I rescued the last Rachni queen. Twice. My friend died curing the genophage. Don't you dare judge me and my crew for things that happened thousands of years before any of us were born!"

She stood and began to pace back and forth restlessly. "We—and by that I mean every being in our galaxy—we are all fighting for our lives, for our civilizations, for our very souls. The Reapers will stop at nothing to destroy us. You want to talk about genocide? About war crimes? About playing God? They've already all but exterminated the Batarians. They're razing agricultural worlds. The Turians are starving!" She brandished the coffee cup in her hand. "This—this—"

"Replicator," Sisko supplied quietly.

"This replicator technology alone could save them. Could save us all," she insisted. "The Reapers don't care about rules of engagement. They don't care who's a civilian or a non-combatant. They want to wipe us all out. They're coming at us not so much like an invading army as a force of—"

"A force of nature."

Shepard's eyes widened, and she froze, all the color draining from her face. "Captain Sisko, please. You can't—"

"Bashir to Sisko."

They were definitely not done here, but the urgency in Bashir's voice demanded Sisko's immediate attention. "Sisko here. What is it, Doctor?"

"Captain, is Commander Shepard with you?"

"She is."

"I need her to come down the the Infirmary immediately. There's been an accident. It's Tali'Zorah."