Disclaimer: I do not own 'Stargate: SG-1', 'The 4400' or any of the characters associated with either show.

Author's Note I: I think that Lily Tyler is the only 4400 character in this chapter non-4400 viewers won't have encountered previously. She is one of the 4400 (disappeared May 26, 1993) Shortly after her return, she discovered that she was pregnant. There was no chance that the baby had been conceived either before her abduction, or after her return. She married Richard, and Isabelle was born approximately nine months after the return of the 4400.

Author's Note II: Best wishes for the holidays to all readers and reviewers. Hope everyone has a great time. :-)

Chapter Eighteen

"Is this going to work – your plan? Taking the 4400?"

"We don't know." 'Maia' said quietly. "When we started, we knew that it might not work, but we knew that we had to try something and none of our other plans had succeeded. The 4400 are our only hope of preventing the future – the world as it is in my time – from coming to pass."

"How... how bad is it in your time?" Sam asked, unsure whether or not she wanted to know the answer to her question. If 'Maia' and her people were prepared to go to such lengths to keep history from repeating itself, it was unlikely to be good.

"Bad." 'Maia' responded succinctly. "Humanity is dying out – and not just on Earth, all over the galaxy. A few of us have been able to move beyond the physical form, to transcend the dimensional planes and transform ourselves into pure energy, but we have been unable to stop the Catastrophe."

"You Ascended." It wasn't a question, but 'Maia' still nodded confirmation. "So why weren't you able to stop the Catastrophe yourselves? Why did you need to recruit us?"

"We were not the only ones to achieve Ascension. There are others, heartless and ruthless, who would rather that the future remains exactly as it is. They like the way things are – the way they will be. If we had attempted to intervene directly, they would have responded in kind. There was no other choice. We tried to keep our plans a secret, to work only through a handful of trusted humans and avoid detection, but they were more resourceful than we had anticipated. When the 4400 returned to this time, they brought the cause of their own destruction with them."

"The sickness?" Sam guessed, thinking that it would be ironic if that turned out to be the case. 'Maia' and her kind had spent so long crafting their plan and engineering precisely the abilities they would need in the people they abducted and their enemies had been able to thwart them simply by giving the 4400 an expiry date.

"No, you must look to the people of your own time to learn the cause of your illness. They chose a different method, an agent of their own, one who is not a 4400 but who has been given the strength and the abilities to prevent the true 4400 from carrying out their mission."

"So they snuck one of their own over the border..." Sam trailed off, remembering her visit to the 4400 Center. "Oh God!"

"Yes." 'Maia's expression was somber. "If the 4400 are to have any chance of succeeding, if the future of humanity is to be saved, then Isabelle Tyler must die."

Janet had been driven to the 4400 Center first, and ushered upstairs through darkened, deserted corridors to be introduced to Matthew Ross and to Kevin Burkhoff. The former had greeted her in polite, though chilly tones, scrutinizing her carefully as though sizing up her potential usefulness, but the latter had been far more enthusiastic, expressing his relief at the presence of a medical doctor and unceremoniously thrusting a stack of files at her for her perusal.

"I figured out what promicin is." He told her as she looked through the files, "that's the name they gave the neurotransmitter, the one that gives the 4400 their abilities, and if I can find one 4400 that hasn't been exposed to the inhibitor, I think I can neutralize it."

Given that any of the 4400 who had attended even one of their NTAC check-ups over the past year and a half or so had been administered the inhibitor at least once, while the few who had managed to slip under the radar were not contactable, that wasn't much help to them, but it was a start, at least.

Although he didn't say anything to them outright, it was clear from Ross' demeanour that neither Tom nor Diana were welcome to remain; it wasn't until the two agents had left the building that he led Janet and Burkhoff outside, walking out of the grounds to the car that was waiting on a quiet side street to bring the three of them to the safehouse.

They had both been obliged to wear blindfolds for the journey.

The house itself was nothing extraordinary, a fairly large suburban house in a relatively high class neighbourhood, outwardly indistinguishable from its neighbours, but once she was inside, Janet found that the home had been transformed into a base of operations for almost fifty people, several of whom were poring over maps and charts in the dining room, discussing the resources at their disposal, in terms of both finances and abilities with Ross.

Several of the 4400 took her up on her offer to examine them, to make sure that they were not carrying the disease and, thankfully, they all seemed to be healthy. However, when she examined samples of their blood under a microscope, seeking the signs Burkhoff had told her of, she could see that they all had the inhibitor flowing through their veins.

None of them had escaped it.

'But if they've all been taking the inhibitor, why are some of them sick and others healthy?' She mused. 'Were different people given different dosages? Is Sam allergic to the stuff, or is she just unlucky?'She was realistic enough to know that her questions might never be fully answered. 'I'll just settle for a cure!'

Matthew Ross was speaking to one of the men, who seemed to be in charge, debating over what their best strategy would be to defend themselves if the government managed to track them down. "I haven't heard from the safehouse in Whelan for a day. We have to assume it's been compromised."

"That's the third one that's gone silent. They're picking us off one by one. We might want to think about fighting back."

"We can do that, Richard. We certainly have 4400s that can do some damage, but once we take that step, there's no turning back."

Hearing snatches of their conversation, Janet felt a chill of apprehension run through her. If Dr Hudson was right, when they found a cure for the inhibitor's effects – she couldn't bring herself to entertain the possibility that they would not succeed – every 4400 in the safehouse, along with thousands of others all over the country and the rest of the world, would develop a superhuman ability. After this, she couldn't blame them if they were less than favourably disposed towards the government that had drugged them without their knowledge, poisoning them.

Even a handful of 4400s, equipped with the right abilities, could do massive amounts of damage if they so chose.

"Excuse me, but shouldn't there be bars on these windows?" Dr Burkhoff had been on edge since they had arrived at the safehouse, unable to focus on anything for more than a few moments at a time, constantly peering out the windows as though expecting government agents to come crashing through at any minute.

"The point is to be unobtrusive, Dr Burkhoff." Ross reminded him patiently.

"Well, this seems a little lax to me. Most of you are 4400s, we're collaborators," he indicated himself, Janet and Ross with a wave of his hand. "You know what they do to collaborators?!"

"We need to get him working." Ross told Richard in a hushed tone. "It calms him down considerably."

"We cleared out a room for you," Richard told Burkhoff, pointing towards it. "Anything you need, just let us know."

"What I need is a clean 4400! One that hasn't been exposed to the inhibitor. I don't guess you've got one of those, do you?!"

Richard's response surprised Janet as much as it did Burkhoff. "Actually, I might."

"No way! I am not going to kill a baby!"

"She won't be a baby much longer," 'Maia' responded, her quiet, placid tone a contrast to Sam's outrage at the suggestion of infanticide. "And we don't want you to kill her. You have your own tasks, and we cannot risk you in a confrontation with Isabelle. She is very powerful, and the outcome would be an uncertain one. You're too important to us."

"In what way?" Sam demanded. "You said that the first time you sent back the 4400, you didn't pick me and your plan didn't work out. What is it that you expect me to do to change that?"

"When we first planned to change history, we concentrated our efforts on changing things on this planet, on averting small problems that would end in having a huge impact, and on sowing the seeds for positive development but we soon came to realize that we needed to be looking at a bigger picture. We knew of your history, of course, every child was taught it, and of the SGC, and we believed that the external threats would be dealt with, but we had not taken them all into account. Whatever changes the other 4400 make, it will be to no avail if Earth is destroyed by another threat. The planet needs to be protected while they do their work. That is what we need you for."

Sam wasn't sure what was more disturbing; that she was apparently well-known hundreds, possibly thousands of years into the future, or that she was expected to single-handedly keep the planet safe from any outside forces that might threaten it. "What if I can't?"

"Then there may be no hope for the future of humanity."

Not an option, then. "What about Isabelle? What have you got planned for her?"

"We have chosen somebody to deal with her – somebody you know, as a matter of fact. Agent Baldwin agreed to help us in exchange for our returning you, and the children, to this time after we sent you back. We charged him with the task of eliminating Isabelle Tyler. He shared your revulsion at the prospect of killing an infant, and destroyed the tool we provided him with." 'Maia' smiled slightly. "It is possible, however, that in refusing to fulfil his end of the bargain, he did us – and the 4400 – a great service. Those who sent Isabelle Tyler back to this time never anticipated that the being they had hoped would kill the 4400 could ever become their salvation."

"But if she's going to help us..."

"It changes nothing." 'Maia's tone was severe. "She must still be destroyed, or she will wreak untold havoc when she grows to adulthood. It will not be long now. You must convince Agent Baldwin to carry out his task, and pass on the weapon we leave for you. The future depends on it."

Isabelle Tyler was a beautiful baby, with chubby cheeks and a thick head of black curls.

"Is that her?" Burkhoff demanded as soon as he saw her.

Richard's pride in his daughter was evident as he introduced her over to Janet and Burkhoff. "I think there's somebody here who wants to meet you. This is Isabelle."

Janet had considered being a paediatrician when she first began to study medicine, but the idea had quickly lost its appeal. As uncooperative as some of her patients at the SGC could be, small children would be far worse. On occasion, she had inoculated children from other planets when there was an epidemic or the like on their homeworlds, and almost every time she had had to give a child a shot, their screams had been deafening, and their tears heart-rending. Cassie had been fifteen before she could take a shot without making a fuss.

When Burkhoff had explained what they would need to do with baby Isabelle, Janet had expected that their task would be a difficult one, with the crying of a frightened baby as their accompaniment, but Isabelle had surprised her by being remarkably cooperative.

Isabelle's brown eyes had been keen and intelligent as Janet gently tied a tourniquet around her arm before sterilizing the skin with a sterile swab and piercing it with a needle, watching her blood fill the vials Burkhoff handed her with an adorably curious expression, utterly fearless.

It should probably have been a relief that she was taking it so well, but Janet found it unnerving.

"There," She capped the last vial and removed the needle, pressing a band-aid against the puncture mark, smiling at the baby who gurgled at her in return. "That's all I'm comfortable taking from her, she's too young."

"Hmm." Burkhoff nodded non-commitally, all but snatching the vial from her hand and bringing it, along with the others, into the room that had been set aside for him while Janet carried Isabelle back to her parents.

When he finally emerged, after what felt like half a lifetime, his expression was triumphant and he held a syringe filled with a bright, almost florescent yellow liquid, staring at it almost reverently, as though he held the Holy Grail in the palm of his hand.

If it truly was the cure, then it was as good as.

"The inhibitor is piggybacking on glucose," he explained to his awed audience. "It enters the brain through facilitated diffusion. It's a binding protein, that's how they did it. But this serum has pure promicin in it, so it can neutralize the charge. The inhibitor won't be able to cross membranes anymore. We can flush it out of their systems."

"So once it's gone, the disease goes away?" Richard clarified.

"Oh, please!" Burkhoff cut in at once. "Stop saying 'disease'. For the last time – it's a side effect. Remove the inhibitor, the immune system functions. It'll happen virtually instantly."

"So, the substance..." Lily Tyler began.

"Promicin." Burkhoff named it. "It's what makes you people unique."

"How did you get it out of my daughter?"

"She has trace amounts of it in her bloodstream – before the inhibitor, you all did. That's how they found it in the first place." He hesitated before continuing, before naming the downside Janet had been expecting ever since he had explained his plan. "But she's an infant. I could only draw enough blood to make one shot."

One cure, for one person, out of hundreds who were sick and thousands who might potentially become sick.

To Janet's surprise, Richard didn't seem to be dismayed by this news, quite the contrary.

"If you can get that into Quarantine, one shot may be all we need."

"I know that it's hard, Sam," 'Maia' said gently. "What we're asking of you and the others, it's a lot, and we know that you have suffered because our plan, that your life has been altered, that it is not as you had hoped it would be, and we regret that it had to be this way, but you must understand how important this is; for you, for your friends, for this planet and for people all over the galaxy. You asked if we could go back and change the past, to choose somebody else in your place, and we could. But we chose you because you are the only one who will be able to carry out the task we have set out for you. We need you to understand that."

"I understand." Sam said softly. The temptation to demand that they turn back the clock and allow her to save her father, to continue her work at the SGC, to live out the life she would have had if it hafd not been for their interference, was almost irresistible but she managed to resist it.

She could not buy an extra six years of life for her father, not when the cost was so high.

'I'm sorry, Dad.'

Somewhere, she hoped that he could hear her.

'Maia' regarded her in silence for a few moments, giving her a chance to digest what she had been told, before holding out one of her hands. "Take my hand, Sam." She said quietly. "I want to show you something."

"What?"

"What's at stake."

Sneaking the syringe into Quarantine had been the easy part; Diana was a well-known, and well-respected agent, so there had been no suggestion that she should submit herself to a search or a scan of any kind. Once she was inside, however, with the cure in hand and a desperate gamble to play, walking past her daughter with it was the hardest thing in the world to do.

Janet could sympathise, and for once, she was thankful that Sam's teammates had not been allowed to enter Quarantine. They would have been hard-pressed not to snatch the cure and give it to their friend, but if Richard was right, then this was the only way.

Once she had reached the bedside of the patient nominated for the cure, Diana tugged down her mask. "Hi." She tried to sound calm and reassuring, but that was easier said than done when so much was at stake. "I've got some medicine for you. To be honest with you, I'd rather be giving this to Maia," she admitted candidly, "but a crazy neuroscientist told me that that was not the right thing to do, so if you don't mind holding still for a minute."

The serum worked as quickly as Burkhoff had predicted it would.

One moment, Shawn had looked as though he was on death's door, a hairsbreadth away from knocking on it, but as the promicin coursed through his veins, he became more alert, pushing against the blankets to get out of bed, to use the ability he had been gifted with.

His healing hands had cured countless people of various debilitating and life-threatening ailments when medical science had been unable to help. Through them, Jordan had raised a fortune in donations, a fortune used to found the 4400 Center, their refuge. Now, they were going to save the future.

Supported by Diana, he made the short journey from his bed to Maia's, placing his hands on her abdomen and closing his eyes tightly as he willed her back to health, dissolving the inhibitor in her system.

She opened her eyes, blinking sleepily at him before turning to her mother. "Mom?"

"Maia!" Diana bent down, hugging her daughter tightly as Shawn, with Janet's help moved to the next bed, to Sam. "Are you okay?"

"Fine," she yawned. "Just tired. Mom," she touched Diana's arm when she saw her glance in Sam's direction, shaking her head almost imperceptibly. "You don't want to know, Mom, trust me."

Shawn's eyes were tightly closed as he held his hands over Sam, his brow furrowed in concentration. Janet watched, scarcely daring to breathe, to hope, as the scar Replicarter's blade had left on Sam's neck faded to invisibility, disappearing without a trace, leaving the skin as unblemished as it had been before. Her eyes remained closed, however, her vitals unchanging.

After a few minutes, Maia spoke up quietly. "Why isn't she waking up?"

Whatever reply Shawn might have made was lost in the steady whine of the heart monitor flat-lining.

TBC.