From the moment that Colonel Sheppard's team stepped through the event horizon and onto the awaiting Nacylian soil, Teyla started to thrash violently against the restraints that kept her on the stretcher the three men carried.

Her passionate struggling got more and more fierce the closer they got to the village and she started making low, threatening noises deep in her chest.

She strained upwards, pulling at the straps around her wrists, trying desperately to get free once they carried her to the center of the Nacyl village where the tribes elders were awaiting her arrival.

A large ceremonial bonfire was lit, various types of alien plants being thrown onto the flame that crackled and filled the air with an almost overpoweringly fragrant smoke and one of the elders came forward, indicating that the stretcher was to be laid upon the ground.

The Athosian gnashed her teeth and snapped at the old man who moved towards her, knowing instinctively that he meant her harm, whether her friends were aware of his intent or not.

A primal howl tore from Teyla's throat as the elder knelt next to her and pressed his palm to her forehead, coated in some sort of aromatic oil.

Her eyes rolled back in her head as the itch beneath her skin--the one that she had thought to be receding--began anew, making her breaths come in short, frantic pants.

She didn't want to change again…she didn't want the beast to emerge.

Whipping her head from left to right, trying to escape the feel of the oil on her skin, the transformation began against her will.

"She is Twofold!" The elder cried as Teyla's body contorted and her bones shifted into a pattern they weren't meant to be in.

Her teeth grew to sharp needle like points, fingernails growing into jagged points and her entire frame started to lengthen. Teyla's voice changed from the human sound it had been to an animalistic rumble that chilled her teammates to their marrow as she cried out in agony.

Watching the transformation of the leader of the Athosians was nothing in comparison to what they were about to witness.

The elder at Teyla's side threw his head back and howled, and the Nacyl that were in the circle around the bonfire raised their own voices in a similar fashion.

"My God," McKay whispered in horror, "They're all…they're all changing!"

The appearance of the Nacyl around the fire began to alter as each of them started changing into the same sort of beast that Teyla had become moments earlier.

One of the straps that held Teyla's left arm to the stretcher snapped in half and she lashed out at the still transforming man next to her, knocking him back with one powerful swipe of her claws. She struggled off the stretcher, tearing what little was left of her clothes along the way and freed herself of her ties.

Breathing hard, slightly hunched over and studying the animals surrounding her, Teyla bared her teeth and roared.

From there, all hell broke loose.

Half a dozen of the transformed Nacyl launched themselves at Teyla, swarming around her and knocking her to the ground.

By sheer strength of will she fought her way out of the clump of beasts, flesh tearing beneath nails and teeth, her only thought for the protection of her pack.

With the viciousness of one who was possessed, Teyla tore apart three of the creatures with her claws and threw them aside, screaming, growling and snarling the entire time.

Teyla's head snapped to one side as she watched her pack defending themselves from a cluster of Nacyl who were rapidly descending on them.

With a primitive growl, Teyla darted in front of the three men to face the animals that were advancing on their position. She stood, yellow eyes blazing, teeth dripping with saliva and the blood of the Nacyl she'd already ripped apart.

The pack of Nacyl stopped moving at seeing her determined stance in front of her friends.

She snarled and pulled herself up to her full height, forearms outstretched, claws bent into threatening hooks and feet shoulder width apart.

"Mine!" Teyla's voice came out in a rumble that was between human and animal, "MINE!"

One of the Nacyl foolishly ignored her stated warning and made for McKay.

With an agility that a creature of her size shouldn't have had, Teyla pounced on the advancing Nacyl, rolling on the ground with it, slashing at it's fur until it was left with a dozen deep gashes. She forced the Nacyl to it's back in the dirt and grabbed it by the throat between her jaws, holding it.

"Mine," she growled again before ripping in one smooth upwards motion, tearing out the Nacyl's throat, "MINE!"

Blood dripping down her muzzle, Teyla batted the corpse of the Nacyl beneath her aside carelessly and resumed her place in front of Sheppard, McKay and Ronon.

Several of the Nacyl fell back and began changing back to their human forms once more.

Teyla's head snapped from side to side as she watched them all transform and fall to their knees in front of her.

Her left eye twitched and she watched them cautiously, suspicious of every movement they made.

The elder who had brought her beast to the forefront of her being, whom she had slapped aside with one mighty paw, shakily stood up.

Teyla scented the air as he tried to approach her.

He smelled different…he smelled…human. Not at all like he had moments before.

"Thank you, Emmagen," he bowed his head low, "You have freed us." He brought up one hand and despite the growling noises that Teyla was making in her chest, he reached forward and tentatively put a hand on her head.

The change was immediate.

Teyla's body gave out and she collapsed on the ground in front of the amassed Nacyl, reverting to her human appearance once more.

"What the HELL just happened?"

---

When Teyla awoke in the Atlantis infirmary, aside from a few blank spots in her memory, her mind was as clear as it had ever been.

Her recollections of what had happened to her on the planet were muddled but her thinking processes were human once more.

"Well, look who's awake." Carson Beckett smiled down at Teyla Emmagen, "How're you feelin' lass?"

Teyla blinked a few times and shook her head, "I am…uncertain. I feel…sore…and confused. The Nacyl? What happened to me? I was…not myself."

"I'd say that's an understatement, Teyla." Carson shifted from one foot to the other, "What do you remember, exactly?"

"Changing," she answered, "I was an…animal?"

"Simply put, yes."

"Why am I not--"

"It's a bit complicated. I think it'd be best to let someone else explain," Carson gestured to the doorway where Orha stood. "S'alright, lass, you can come in now."

Orha took a few measured steps forward but didn't meet Teyla's eyes, "You must forgive my people, Teyla Emmagen…we deceived you and your friends so that we might end the curse that was upon us."

"I do not understand."

"The only way for my people to be free of the infection was to find the Twofold who was intentionally keeping the disease alive and kill him. I fear we used you as…bait. "

"You intentionally infected me?"

"No…that was Sidnal's doing. He was a Twofold but not the one we sought." Orha locked eyes with Teyla, "He wanted to take you as his mate and he infected you. But with the cleansing ritual, we forced the suppressed Feral in all of us to surface, knowing that you would instinctively find the remaining Twofold and execute them. Then we would be free of the infection."

Teyla narrowed her eyes at Orha. "How?"

Carson cleared his throat, "I can answer that one. Apparently, a Twofold secretes some kind of hormone that causes the infection to remain active instead of dormant as it's supposed to be."

"We are not in control of our own actions to a certain point because of it, Teyla Emmagen," Orha added shamefully, "Nor are we able to identify the Twofold responsible."

"But an infected outsider can," Teyla finished for Orha.

"Yes."

"Am I still…infected?"

"The infection remains dormant in you as it is intended to. For your assistance, forced though it was, you have received enhanced senses and strength." Orha looked up at Teyla. "I will not lie to you and say that I am sorry that you helped us, but I am sorry that you were forced into it by Sidnal."

"Will this not happen again, when another Twofold is born to the Nacyl?"

"No," Orha answered quickly, "Your Doctor Beckett has had time to study the infection and find a way that will insure that no more Twofold are born to my people."

Teyla sat back heavily. "Then I am glad. I would not wish that transformation on another living creature."

"Thanks to you and your pack, Teyla, none will be forced to transform ever again." Orha bowed reverently, "You have the deepest gratitude of the Nacyl."

Teyla couldn't bring herself to say 'You are welcome' so she just nodded as the young Nacylian woman left the infirmary.

"Doctor Beckett?"

"Yes, Teyla?"

"Are you certain that I am not going to transform again?"

"You have my personal guarantee that you won't, Teyla. You've just got enough Nacyl DNA to make your senses more acute…no danger of you turning into a beastie out of the blue ever again." Carson patted her arm with a smile, "Best get some rest now, hm? You've had a long few days."

He pulled the blankets up higher over her and she touched his hand, "Thank you."

"Think nothing of it."

-

A/N: Roll credits!

-falls over-