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AN: This is the first in a series I've come up with looking at how the War Doctor might have taken action to cut off potential other areas of conflict during the Time War by preventing other conflicts from escalating to a point where either side could have used something from that war for themselves.

Doctor at War: Ending the Xenomorph

With the Alien Queen dealt with at last, Ellen Ripley was relieved to be able to focus on less immediately life-threatening matters. Bishop and Hicks had been placed into the stasis chambers to protect Bishop from further damage and prevent Hicks' injuries getting any worse, but she'd left Newt in the stasis chamber to rest while she took a last check over the ship to make sure that everything was in order.

It might be fifty years ahead of the Nostromo, but she'd always been fairly adaptable and she'd had time to give herself a crash course in some of the technical advances since her time before Burke had asked her to go back to the colony. Most of the controls had remained fairly similar to her time, even if the computers were a bit faster than they had been; she guessed that people were going by the idea of 'if it ain't broke, don't fix it', but beyond that she didn't see the need to consider it any further.

She had just entered the docking bay to make sure that the shuttle was all right when she was startled to see an unfamiliar man looking up at the ship in a critical manner. Acting on automatic, she called out to the new arrival, only for her jaw to drop in shock when he turned to reveal his face.

"Kane?" she said, staring at the man incredulously. He had a neatly-trimmed goatee that she'd never seen him wear before along with a face that seemed to have seen far more, as well as wearing a leather jacket that didn't fit with Kane's preference for more casual attire, but he really looked like her old shipmate…

"No," the man said, shaking his head as he looked solemnly at her, demonstrating a calm control that Kane at his best had never managed to express. "I'm not Gilbert Kane; I'm just a concerned soldier looking for something."

"What-?" Ripley began, before she saw something just behind him; two oval objects, slightly larger than a human head, with a distinctive opening on the top.

They were slightly smaller than the things she had seen during her first visit to the godforsaken planet below them, but Ellen knew what they were immediately.

"Eggs?" she said, staring at them in outrage. "That thing had time to lay two eggs?"

"Those xenomorphs have an unusual and rapid lifecycle, Lieutenant Ripley; the Queen's whole purpose is to ensure the spread of the species," the man explained. "I was in the area and felt that it would be best to collect them-"

"To take them back to your corporate masters, is that it?" Ripley spat indignantly, quickly studying her surroundings for a weapon of some sort; even if this guy was a synthetic, she knew from experience that they could take more damage than a human, but the right blow could still shut him down-

"On the contrary," the Kane lookalike said grimly, "I'm here to destroy them."

"What?" Ripley said, momentarily defused by the simplicity of his denial; Ash might have lied to get them to the original ship, but he'd always done that by manipulating the truth rather than explicitly lying when confronted directly…

"My appearance may be a shock to you, Lieutenant Ripley, but I can assure you that my resemblance to your old friend is nothing more than a strange coincidence," the man explained, his solemn tone convincing her of his honesty more than anything else. "I am only here to ensure that these… things… never go any further."

Ripley knew that she should be more jaded after some of her past experiences with corporate representatives, but something about this man, beyond his resemblance to Kane, made her step back and give him a chance with the eggs. As she watched, the man took a small silver rod out of his pocket and pointed it at the two eggs. A red light glowed on the tip of the rod, and suddenly both eggs cracked and shattered as though they were conventional eggs rather than the hardened leather she'd felt when she'd made contact with them in the past. Two half-formed 'facehuggers' lay amid the strange slime that apparently served as amniotic fluid, their legs twitching but otherwise displaying no trace of the rapid scurrying she was used to seeing.

"Are they…?" she asked, looking uncertainly at the creatures.

"They're dead," the man said, turning back to face her before he reached into his pocket and tossed her a small phial of something. "You might want this; it's a nanite solution I found that should facilitate the repair of your android in the stasis chamber."

"Bishop?" Ripley asked, looking at the tube in surprise; nanites were a theoretical possibility, she knew, but the last she'd heard they were one area science hadn't cracked even after her decades of cryogenic sleep. "How-?"

"Even the best of your scientists would have trouble understanding them, and they'll have run down by the time you reach your destination; just inset them into the android's tube, and he'll be back to normal when you arrive," the man explained.

Bemused at the explanation, but still seeing no reason to doubt his words, Ripley pocketed the phial he'd given her, making a mental note to take a closer look at its contents in the lab before giving it to Bishop; this ship might not be a science vessel, but its lab still had a decent microscope.

"Who are-?" she began to ask.

"Just an old soldier, Lieutenant," the man said, a sudden weariness about his manner that made Ripley believe it; he might not look much older than her, but something about him hinted at a far greater age than appearances might suggest. "One who wants to see that this weapon never goes beyond the events on that planet…"

Lost for anything else to say to that, Ripley simply nodded at the man in understanding as he turned around and walked off into the side hold where she'd acquired the loader she'd used for the final confrontation. For a moment, Ripley simply stared after him in confusion as he walked into the shadows of the hold, but when she heard a strange wheezing, groaning sound, she hurried after him, only to find herself facing an empty room, with no sign of the strange arrival or anything that could have caused that sound she'd just heard.

She had no idea what had just happened, but if it meant the end of the creatures that had destroyed two of her crews, she could live with a little mystery in her life.

That said, if he'd found those two eggs when she'd been unaware that there had been any here in the first place, she'd take a final check around the ship just to make sure…

AN 2: So, as a first story in this series, what did you all think?

I have a few ideas for other series I might use, but other suggestions would be appreciated; I'm looking for anything where the War Doctor showing up briefly at the right place and time could have ended further struggles for good if he acted in a more decisive manner than other Doctors would have done (Anything involving magic is out to make it simpler, so don't ask me about Buffy or Supernatural)