"It isn't your fault, 'Lilah."

Shepard glanced up from the sample data in front of her, the keen start of a serious headache knifing behind her eyes, and looked at Traynor, who had seated herself beside her.

"There are fourteen million people on those ships, Sammi," she said softly. "Fourteen million people, trapped and with nowhere to go."

"Yes, but it very well may be fourteen million people that you saved, by figuring out her target before she could strike."

"And if they don't get there in time? If it's already happened?"

"Then there will be survivors. They wear their environmental suits constantly, 'Lilah- even on board their own ships. They're incredibly sophisticated, designed to prevent any kind of foreign body from entering. I know this Osco is smart but…"

"There aren't any foreign bodies, remember? We haven't been able to pinpoint a single-"

She suddenly broke off, her dark brows knitting as she straightened, staring at the scrolling data in front of her.

"I remember that look," Traynor said. "You've just thought of something."

"There aren't any foreign bodies because there aren't any foreign bodies," Shepard said softly.

"And…I also remember those confusing explanations of yours that didn't really explain anything," Traynor replied, but Del ignored her, already getting to her feet.

"Dr. Solus!"

He broke off from his own work station, heading her way. "Dr. Shepard?"

"I need a direct look at those contagion samples in the hot lab."

"You have all data extrapolated-"

"No, the data is no good. I need to see them for myself."

"You have a theory?"

"Yes, but I need to verify it. We still have the lab animals in there? They're still doing fine?"

As she spoke, she was heading to the decom lock, where the helmet to her static suit was hanging. Feris, who was back on shift, straightened from the wall.

"Where are we headed, Doc?" she asked.

"The hot lab," Shepard replied, pulling her helmet on and locking it down as Mordin and Traynor did the same. Feris locked hers down as well, following them into decom.

As they headed outside and across the square to the mobile hot lab, Shepard was visibly anxious. "Mordin, are you familiar with the research that I was doing on Virmire under Osco, before the funding was pulled?"

"Yes, have read reports. Isolate inter-species genetic resistances to disease and manipulate for use in other species to spread resistances. Ambitious."

"And impossible, as I understand it," Traynor said, trotting to keep up. "Didn't they pull funding because there were no verifiable or duplicable results?"

"Yes, they did," Shepard said, reaching the other decom chamber. Within this mobile were not only the static cells holding Delphine and Domingo, but also all the tissue and blood samples drawn from the various victims. "At one point, Osco had the wildest theory…"

"Wild theory?" Feris asked as they entered into the lab. Domingo appeared to be napping, but Delphine was awake, getting to her feet and watching them as Shepard immediately made for the samples and the few cages of animals they'd been testing on. Drawing a case out of the anti-pathogen field she opened it, taking out an infected blood sample and loading it into a syringe. Then, she drew a fresh sample from a rabbit in a second syringe.

"All the testing so far has been to inject the animals directly with infected blood or tissue samples, or with the direct contagion samples from the crash site," she said.

"Correct," Mordin replied. "Also, produced aerosol from missile site samples and introduced into air to determine if inhaled transference had more effect than injection."

"And in each case, the animal was just fine. No symptoms whatsoever. All further blood or tissue samples from the animals showed no sign of damage or contagion- absolutely nothing abnormal."

"Correct."

Shepard plugged the two samples in to one of the computer consoles. A split screen holographic display appeared, showing a highly magnified view- human blood cells on the left, and the rabbit's blood cells on the right.

"The thing is, there should have been an abnormality," Shepard said. "How long was it between initial injection and the first blood sample from the animal?"

"Thirty seconds for first sample, two minutes for second, half an hour for third. Yes, I see what you are saying-"

"Can you tell the rest of us? Some of us aren't geniuses," Feris asked with a gentle smirk.

"Say you inject human blood into a rabbit's blood stream," Shepard said, her fingers moving quickly over the console controls. "Then, thirty seconds later, you take a sample of blood from that same blood stream. Thirty seconds is long enough for the rabbit's circulatory system to dilute the human sample and spread it across the body, but it isn't long enough for the body's system to break down or eliminate the human blood cells that were just introduced. So any sample taken from the rabbit within thirty seconds should show traces of human red cells still in its bloodstream…you've just introduced them there, after all. These would be considered foreign bodies."

"But no foreign bodies detected on immediate testing," Mordin said. "Only rabbit cells. Human cells unaccounted for."

"And no one noticed they were missing?" Traynor asked, surprised.

"Focus on locating pathogen or damage to indicate presence of infection, not counting human cells in rabbit blood," Solus replied. "Easily missed."

"So, on my right here I have healthy rabbit blood cells. On the left, human blood cells taken from an infected patient. If I combine the two by hand, what should result is a mixture of human and rabbit blood cells."

Shepard hit the last command. The holographic interface changed as the computer drew the blood samples from the syringes and combined them in a single test tube. On the image, the cells mingled, exactly as expected.

Then, less than four seconds later, the human cells suddenly shifted and changed. Traynor's eyes went wide.

"Oh, my God! They're…they're changing into rabbit cells!"

Within ten seconds the sample in front of them showed only rabbit blood cells, with no trace of any human cells or residue. Shepard's hands felt cold as she stared at the screen in awe.

"She did it," she said softly. "Polyneuro-mimetic DNA. There is no foreign body, no carrier…because the disease is the DNA itself. It's a biological computer virus."

"How can it be a computer virus?" Feris asked.

"DNA across species just biological computer code, basic programming information," Mordin explained. "Can be reproduced in actual computer code, and tech exists to program computer code onto biological matter, encoding it on DNA."

"That's how cyberorganic computer chips work," Traynor told her. "Information is actually encoded onto proteins in the organic fluid. But this…'Lilah, what you're suggesting…we're at least three hundred years away from this kind of tech-"

"No we're not. Not any more, not thanks to Osco," Shepard said softly. "Osco became obsessed with PMD during our project, for a while anyway. A generic non-specific program encoded onto sterilized DNA strands or end caps that would be compatible with all known sentient species. Once introduced to a natural set of DNA the PMD program would initiate, overriding and rewriting the natural coding of the host DNA and correcting the genetic flaws responsible for hundreds of different diseases. It would then replicate itself through the system, systematically replacing the host DNA with the corrected copy until the program was spread across the board, throughout all physical systems. It would become that person's actual genetic code, passed on through their offspring. But it was impossible. Like you said, the tech was three hundred years away. It would take a supercomputer years just to extrapolate the base code in every sentient species…just to give us a place to start."

She was still staring at the sample glimmering in light above her. "But she did it. Somehow, she actually managed to do it. Oh…my God, Wyatt was right. He was right…he knew I would figure it out, and he knew I'd know why."

"Why, 'Lilah? Why is she doing this? What does she hope to achieve?" Traynor asked, putting a hand on her shoulder.

"Delphine," Shepard said.

"What?"

"Delphine! Delphine is what she hoped to accomplish," Shepard said, pointing over at the girl still staring at them. "Delphine is the success of this project, the entire point. Evolutionary perfection on a genetic scale. It all has to do with the PMD."

She walked over toward the girl's cell, regarding her with a mix of wonder, horror, and sadness. "The moment the PMD is introduced to a host, it samples the native DNA. If the DNA is too flawed for its purposes, the PMD eliminates it from the gene pool. With certain people, the body systems respond to this testing with a histamine reaction, causing them to cough and sneeze. The histamine acts as a carrier or an initiator. This causes the PMD to congregate in the heart fibers and circulatory system, where it promptly dissolves the DNA and nuclei of the host cells, rupturing them, millions at a time. As a result, we get massive amounts of coronary damage and swiftly, death."

"Those that go crazy?" Feris asked, and this time Mordin answered.

"No histamine reaction to draw PMD to heart, instead congregate to neurologic material. Destroy blood-brain barrier, invade brain cells, destroy. As brain decays neuroses, hallucinations, violent behavior begin…then death. This reaction good to Osco's agenda…allows infected to infect others swiftly via fluid exchange. Bites, scratches, compromised mucus membranes."

"Then in others, the base code still isn't right, but its close enough for the PMD to try to start working. It tries to replicate and rewrite its code but flaws instead lead to mutations and eventually kill the subject," Shepard said. "Then, sometimes-the PMD infects a person who is just right. Their DNA has all the required traits to allow rewrite without flaw or destruction, their immune system is just right to prevent a histamine reaction, and the PMD is allowed to work. Perhaps the scale is one in a hundred…maybe one in a thousand, or a hundred thousand- but on those individuals, we see what is happening with Delphine. Body systems are improved by staggering amounts. Muscles are made stronger, healing faster, the immune system more powerful. All those pesky genetic diseases and carriers and recessive alleles are done away with. The PMD works, and as a result, you get absolute genetic perfection in the patient. Delphine is going to become the perfect human, all the garbage cleared away."

"This is…this is Osco's idea of eugenics," Traynor said, horrified. "That's what she's doing, isn't it?"

"Yes," Shepard said. "She doesn't care about the trillions that die. In her mind, she's just clearing away the garbage. If their DNA isn't suitable for perfection, then it's junk and needs to be completely removed from the gene pool. The few thousands like Delphine- millions, maybe, out of the entire galactic population-these will be the perfect ones, utterly ideal specimens free of everything she considers a flaw."

Osco had always been obsessed about perfection. Shepard had thought it was merely her anal retentive nature…she had no idea that it stretched so far. Osco absolutely abhorred chaos.

This is her answer to chaos. This is her way of putting order to sentient life. She's rebuilding them from the microscopic level up.

"What about Domingo?" Feris asked. Shepard blinked out of her thoughts, unaware that her lashes were damp. The monstrosity of all of this was hard to comprehend.

"What?"

"Domingo. He's immune…"

"Oh, yes. It comes down to PH," Shepard said. "PMD can only live in certain wide-average body chemistries. That's why it needed the suspension fluid in the missile. It dies very quickly outside of its environment. There are going to be some rare members of each species who have a natural body chemistry just off enough the PMD dies when it comes into contact with it. Domingo isn't actually a carrier because any infection is killed quickly on entering his systems…it can't stay around long enough to transfer to or infect anyone else."

"Does that mean I can get out of here?" the man asked. He'd woken up during the conversation and heard most of it.

"Yes, actually. If I'm right, there really is no reason to keep you or Delphine imprisoned. Any PMD in her system is already locked onto her DNA to rewrite it and won't be transferable."

"You're sure about that, Doc?" Feris asked.

"Oh, absolutely. Here, I'll show you."

She unlocked and opened the door of Delphine's cell, moving so quickly that by the time the marine realized what she was going to do, she was already inside with the door latched again.

"Bloody Christ, Doc! Stop!"

"I told you, it's safe," Shepard said, removing her helmet. Delphine was blinking at her like a deer caught in headlights, and Sam slammed a fist against the side of the protective glass.

"Fuckin' hell! Get the fuck out of there!"

"There's no other way to prove to you they're safe," Shepard told her. "I'm sorry, Sam. I know you're supposed to protect me, but I couldn't ask anyone else to do this. I wouldn't do this unless I was absolutely sure. I'll be fine."

She set her helmet down on the bench and then unabashedly reached over, hugging the young Delphine tightly and kissing her on the cheek. "You're going to be just fine," she promised softly.

Tears shimmered in Delphine's eyes, spilling down her cheeks. "You said it was changing me…"

"For the better. You'll be stronger, faster. You won't get sick, you probably won't even age any more…at least not anywhere near the rate we do now."

"I-I will still be me?"

"Of course you'll still be you…just you, plus."

"Doctor, you realize will have to stay in there for two hours," Mordin said, his words renewing Commander Feris's scowl and causing her to slap the glass again. "No symptoms by then, will be safe to release."

"I know. I'll be fine. At the very least, we know I'm not going to drop dead of a heart attack…I'd be coughing by now."

"Will keep you under medical surveillance, continue tests on samples to verify results."

Traynor moved over to the glass and laid her hand on it. "'Lilah, I can't believe you did that. What if you were wrong? What if you are wrong?"

"I'm not," Shepard told her, loosening her hold on Delphine and looking at her. "Sammi, you saw it yourself. Wyatt knew that I'd figure it out, so did Osco. I knew about her earlier obsession with PMD. I knew about her obsession with perfection. There are no foreign bodies found because there are no foreign bodies- at least not recognizable ones."

"Then how come we couldn't find the PMD before? The water samples, the spore samples, there's no trace of-"

"Because it hides. When it's not in a targeted host that it's been triggered to interact with –in this case, a member of one of the galactic sentient species- it hides. It simply copies the improper host DNA and changes itself to mirror it, rendering it immediately inert the moment it makes the metamorphosis. It's a self-erasing virus. You saw the screens, you saw it happen. The PMD is just raw DNA strands and end caps floating around in the sample fluid…far too small to be noticed unless we were specifically looking for it, and even then it would look like impurities in the solution. That's why we saw spore overgrowth at the crash site. When PMD touched the DNA of the natural spores, those strands replicated it, and made itself inert. So much of it replicating into spore DNA created more spores. It's as simple as that. They're harmless."

"It's what I said about the quarians, isn't it? About foreign bodies being filtered through their suits. That's what made you think of all of this."

"Yes. The only way it could get through the quarian's protections is if the protections thought they were allowable molecules. PMD would be released into the ship's atmosphere by the ship's own hydrolyzers. The environmental air balance in a quarian ship isn't just oxygen and water. There are several small nutritive or even beneficial microbes that are cultivated and released as well. These are essential for lung health…probiotics for the respiratory system, if you will. The PMD would have mimicked these expected microbes and the suits wouldn't have filtered them out, recognizing them as natural bodies meant to be there, instead of foreign ones. I realized the only way to do that would be if Osco had actually managed to make PMD."

Traynor smiled sadly. "No wonder she wanted you dead," she said. "No one else would have even thought to look for tech that shouldn't exist for centuries yet. No one else would have had the background in her theories and obsessions."

"Yeah," Shepard replied. Stepping up to the glass as well, she put her hand on it in mirror of Traynor's. "Unfortunately, that was the easy part. Vaccinating against it or curing it…now that's going to be a trick and a half."


Liara moved carefully though the quarian live ship…the fourth she'd now boarded. Behind her, Jondum Bau and his two human Spectre candidates were flanking her, all weapons up, silent and listening.

Jondum Bau was a salarian Spectre that Liara had worked with before. Tall and lanky, even for his species, he was efficient, calculated, and deadly at his work. The two human N7's he'd been asked to observe were both male. They had never been officially introduced but she knew them well enough from their dossiers.

Kaidan Alenko was the smaller fellow, a biotic who had distinguished himself time and again. The other, much larger fellow was James Vega, almost half again Alenko's physical size and nearly a walking wall in his own right.

All four of their faces were set and grim as they proceeded through the ship, stepping carefully over dead quarians littered everywhere, ears open for any sound of threat or call for help.

Most of the dead seemed to have died fairly quickly where they'd fallen. Others were bloody messes, having torn off their helmets…or having them torn off for them. Some were shot.

Some were children.

Room after room they moved, door after door, corridor after corridor. Motion suddenly burst out in front of them and every rifle swung forward as a quarian male ran at them. His helmet was gone, as was half of his face. Blood coated the neck and chest of his environmental suit, and he was failing his arms, laughing hysterically as he charged.

Bau's bullet took him neatly between the eyes, and he folded with a wet, heavy flop onto the ground.

"Statistically, we should be seeing more survivors," Liara said. "On Purdue, only forty percent died within twenty minutes. The numbers I'm seeing here suggest sixty or even seventy percent, and not a single immune as of yet."

"Physically, quarians are far more fragile than humans," Alenko said. "Surely that's why."

"They have their issues but quarians are surprisingly more robust than most people think," Liara replied. "It is more likely that this plague simply works on every species in differing ways, and in different proportions. It-"

"Help me!"

The voice was distant, frantic. The four halted, listening carefully. After a moment it repeated ,riding on a terrified sob.

"Someone, please…if anyone can hear me, I need help!"

Just ahead there was a juncture. The voice was calling from the right, and Liara gestured that way. Jondum pointed to Vega and gestured left, the big human man nodding in reply.

Edging carefully around the corner to the right, Liara saw an open doorway, and a heavy streak of blood that lead into it. Within, thick sobs continued to echo. Leading with her rifle, she moved up to the door and peered within.

A quarian man lay dead in the middle of the room, the source of the blood smears. He appeared to have been shot. Further in the room, a terrified quarian woman was holding tightly to a young child, probably only five or six years old. The child was fighting with her, slapping and tearing his hands at her suit, nonsensical and furious syllables spilling in an endless tirade out of his mouth. At the woman's hip, a pistol rested on the ground. Liara felt her heart sink as she realized the situation.

The man had been infected and gone mad. He'd attacked them, perhaps his own family, and the woman had been forced to shoot him. Unfortunately, the child had also gone mad. Not strong enough to actually compromise or damage her suit, it did not stop him from striking out as frantically as he was able.

She could not tell if the female was genuinely immune and unaffected, or if she was in the first stages of the illness that lead to mutation. As she saw the asari peering in she sobbed again.

"Please, please you have to help me. He's scared, I-I can't control him..."

Liara kept her gun up, but held out one hand to show she meant no harm. She edged forward another pace, then two. "Ma'am, I am going to put him in a biotic bubble…restrain him. Are you feeling ill?"

"Wh-why would Kal d-do that? Why would he attack us?" The woman asked, too upset and traumatized to think rationally. "H-he was our friend, why would he come after us...?"

"He could not help it, he was very sick," Liara said, shifting forward another pace. "I need to know if you are feeling ill."

"S-someone should tell the captain…someone should tell the Admirals about what's going on…"

Tightening her jaw, Liara reached out with a biotic field, snaring the kicking and screaming young child and holding him motionless. Though he could not move, he could still scream…and scream he did.

Though she had warned the mother of what she was going to do, the quarian recoiled in startled fear, then wailed frantically.

"No! What are you doing to him? He's just scared!"

"Ma'am-"

"Let him go! Let him go!"

"She's losing it," Bau warned softly from her elbow. A breath later, the woman lunged for the pistol, snapping it up toward them.

Liara still had her rifle on the woman, holding it one handed with her other controlling the biotics. As the woman swept the pistol upward Liara fired, spanking a bullet harmlessly off the wall nearby. The sharp bark of the weapon going off startled the quarian again and she jolted back, dropping the weapon in her hand.

"Ma'am, listen to me. I am not hurting him. He is very ill and I am merely restraining him so he does not hurt you or anyone else. We can get you off this ship but I need you to cooperate with us, all right? No one is going to hurt you or the child."

Cowed, trembling, the woman nodded slowly. "A-all right…"

"Now. Are you feeling ill? I need to know."

"N-N-No, I…sick? No…i-is that what this is? They're all sick?"

"Yes, and we are trying to help as many as we can. We are going to help you. Is this boy your son?"

"M-my nephew…"

"What is his name?"

"N-Nika…"

"Nika. And what is your name?"

"Muusa."

"Very good. Muusa, I am Liara. I am a Council Spectre."

She tilted her head, and Bau waved to Kaidan, who appeared in the doorway.

"This man is Kaidan Alenko, he's an Alliance officer. He's going to take you and Nika to a medical evac ship for help. He'll keep you both safe."

Kaidan nodded to her, reaching his hand out and taking hold of the dark energy holding the boy motionless. As he did, Liara lowered her hand and let her own biotics die. Then Kaidan held his free hand out to the woman. "C'mon. Let's get you somewhere safe."