Callie chewed on her lunch slowly - well, it was supposed to be her lunch, it was a container full of strawberries that she had packed herself before leaving the house. She hadn't actually had the chance to sit down and eat it because the emergency room had been so unbelievably busy. And only now, at the very end of her shift, had the ER fallen quiet and given her the chance to clock out and eat her lunch-dinner outside on a bench in the cool London air.

The ambulance bay just outside the emergency department was quiet, uncharacteristically quiet for a weekend evening. She supposed it was hardly her problem now. She didn't look up when a figure sat next to her, until from the corner of her eye she saw it didn't appear to be one of her coworkers, instead it was a man in a tweed jacket and bowtie.

"You look like you just got back from a particularly rough bar mitzvah," she commented, tilting her head at the man. She held her container out for him. "Strawberry?"

The man turned to look at her and she was immediately struck by just how old his eyes seemed. He was young, surely no older than 35, but there was a wisdom and hurt in his gaze that she'd only seen in her oldest patients, usually veterans. And he looked like he was in pain, so much that it made Callie hurt just being near him.

He shook his head, offering her a sad looking smile. "No thanks, looks like you need them more… a bar mitzvah?"

"The bowtie," she pointed out, gesturing to her own neck. She gave him a smile. "It's very, ah… 13 year old boy."

"This bowtie is very cool, I'll have you know."

"Never said it wasn't," Callie said with an amused grin, still holding out the strawberries to him until he finally relented and took one. She nodded in satisfaction, gesturing to the hospital behind them. "What're you in for?"

She scowled a bit when the man bit into the strawberry and immediately let it fall out of his mouth, muttering under his breath that it was disgusting.

"Palliative care," the man admitted as he spit the last of the strawberry out. "Visiting, I mean. Seeing an old friend."

Callie's face dropped, a strange mix of guilt and empathy crossing her face, like she regretted asking. "I'm sorry. At least you had the time to say goodbye." She looked away from him. "It's the one thing we can't fight, time. It marches on."

"Well, I suppose not," the man shrugs, looking at her. "Not for now, not for… a while."

"You could be right. Matter of time before a new alien pops in offering us time travel and immortality," Callie chuckled, leaning over and offering an elbow for him to bump. "I'm Callie, by the way. I work in the ER."

The man bumped his elbow to hers confidently. "The Doctor! Just The Doctor, always The Doctor!"

"Alright, The Doctor," she scoffed a bit in amusement. "Maybe I should have introduced myself as The Nurse then. Got a real name?"

Before The Doctor could open his mouth to answer, their conversation was cut off by wailing sirens, an ambulance swerving wildly as it came into the bay, screeching to a stop concerningly close to a concrete wall. The Doctor immediately stood, but Callie stayed in her seat, her chewing of a strawberry paused, her whole body looking frozen.

Her shift was over, she tried to tell herself. Someone else could handle it.

The doors of the ambulance swung open and they could hear immediate screaming, one of the paramedics popping out and screaming for help. There was a clatter as Callie's container fell to the ground, abandoned as the woman rushed to help, The Doctor hot on her heels.

She never could resist someone shouting for help.

"Oh my god!" Callie exclaimed when she stepped up into the ambulance, her eyes wide as she watched the patient's stomach bulge and move, his skin stretched taut as if something was trying to escape. "What is that?"

"I don't know!" The paramedic said, panicked fear written on his face. "We think it's a hernia, is it a hernia? Please, God, tell me it's a hernia!"

"Does that look like a hernia to you!?" Callie said, sitting down beside the patient and checking his pulse at his arm. "How long has he been in v-tach?"

"The whole time, I'd expect!" The Doctor said as he stood in the entryway, looking much too excited for a man standing in front of a complete medical horror. Something about it made Callie angry, that a man was clearly in so much pain and he was smiling.

"Are you really a doctor?" Callie asked, looking terrified as she glanced up at him, the patient's heartbeat growing ever faster. "I've never seen anything like this, can you help?"

"Well it could be one of two things," The Doctor explained, pulling out a strange tool and scanning it over the body. "It can't be adipose, not now they've gotten their breeding planet back-" He paused to apparently read something on the scanner. "Oh, you beauty-"

Callie wished she could say she was brave for the next part, that she had sat and handled the sudden guts on her face with dignity, but unfortunately that would be a lie. When she saw the patient's stomach burst open she screamed, and when she saw what came from his stomach she screamed louder. And then, when it latched onto the paramedic's face she stopped screaming, mouth wide open with horror.

And when the patient's heart monitor flatlined, it was as if everything in Callie that had just frozen had thawed and she leapt forward. The screaming and shouting of the paramedics and the excited rambling of The Doctor registering blank to her ears as she tried to get the patient's heart going again.

But no luck, Callie did compression after compression but she knew she was lying to herself, so she pulled back, and she checked the watch on her shirt. "He's gone," she mumbled, looking up to see the Doctor had just pried the creature from the paramedic's face. The guy was being tended to by his partner as the Doctor continued to use his scanner on the still moving creature.

"20:42," she mumbled.

Just in case anyone was still listening.

The creature was still trying to leap onto someone's face, and it was making Callie angry. That thing just killed a man, and tried to kill another and the Doctor was praising its beauty. So she grabbed the thing's lashing tail and swung it into the wall as hard as she could.

"What are you doing?!" The Doctor shouted, panicked and looking upset. He picked up the now limp creature, looking it over. "What would you do that for?"

"I don't know, it just killed a guy and tried to kill him!" She gestured to the pale and panting paramedic. "That thing just burst out of a man's stomach and you think a whack against a wall killed it?"

"You-" The Doctor looked incredulous, standing up and stepping out of the ambulance without another word.

Callie was quick to follow. "What is that thing?" She called after him as he approached a blue box. "You know what it is, we need to be looking out for it!"

"No, what you need to be doing is going to help that man in the ambulance!" The Doctor called over his shoulder. "You need to go back to your job, back to your little life and, well, leave it to the experts."

"Oh, yeah, now I believe you're a Doctor!" Callie scoffed at the audacity of his words, frowning when he began to unlock the door of the box. As soon as he stepped inside she ran to follow him. "I don't want fame for discovering it or anything! I just want to help people! What are you doing in there?!"

She stepped into the box and paused, looking around in confusion. She supposed it wasn't the weirdest thing she'd seen today. She rushed up toward where the Doctor was and stood next to him as he plugged the creature up to something.

"So what is it?" She asked, making the Doctor jump.

"Oi! What are you doing in here? Get out!"

"You left the door open," Callie pointed out. "And I'm not going anywhere 'til I get answers! That thing just killed my patient, so I'll need to know everything. What are we dealing with here? Definitely aliens, yeah?"

"Yes," The Doctor nodded, looking a bit impressed with her persistence as he snapped his fingers to shut the door. "Definitely alien- did you notice the room by the way? I like when people notice the room."

"I did! Nice place, bit grey!" She said, still looking over the creature, growing hyper focused on the thing. "It's all very Sigourney Weaver, isn't it? It's too on the nose- like a spaceship crashing into Big Ben on the nose."

"Yes! You're right- well, not really but it's a good guess! In fact, if anything, Sigourney Weaver is all a bit this! This here is the original, the inspiration!"

"You mean this has happened before? How long have these things been here? And why don't we know?" She looked at the screen the Doctor pulled over, unable to read the words there and frowning. She hated being out of the loop.

"A millennium!" The Doctor read, amazed.

"But that guy was barely 50, right?"

"Right, but this creature alone isn't a thousand years old, it's only as old as the man it came from! The seed was, well, planted then!"

"So how did it get into him, was it being passed down, like a gene?"

"Oh, clever Callie!" He looked to her with a beaming grin. "Very clever! It was planted back then and it's been passed down, growing, changing, evolving until it could survive in the world!"

"So it could've happened before and it just wasn't ready, say in the 70s?"

"Sigourney Weaver!" The Doctor laughed. "But it seems ready now, for whatever its purpose is now."

"Well then what's the purpose? And how do we stop it from killing more people?"

"If it's been here for a thousand years than the strain has been growing, spreading… it could be all over the world by now!"

Callie's face dropped, and she looked up at him. "Doctor," she said. "How many people?"

"I don't know, I don't…" Something else came up on the screen. "There's no way to stop it now, we'll have to go back and stop it at its source! We have to find what planted the seed!"

"It's a thousand years old! If it's been evolving that long then whatever planted it is long gone…"

The Doctor stepped away with a laugh. "Now see, Callie, that's where you're wrong!" He said as he flipped a lever. The console before them began making noise and the ceiling began to spin and Callie looked around, scowling. "We'll stop the seed from being planted at all."

"Okay, we don't need a merry go round, Doctor, we need a solution, an- an antidote! We need to take this thing to WHO and develop an antidote!" She turned around to walk towards the door and behind her back The Doctor had a sly grin on his face.

She stepped out, freezing when she heard her foot crunch in thick snow. She looked down at the white ground beneath her feet and took another step out, smiling a little childishly at the crunchy sound her feet made on the seemingly fresh snow.

Then she looked up and the ambulance bay she'd just been in was gone, replaced with a sprawling snowy forest. She looked back into the box.

She opened her mouth to speak. Nothing came out.

The Doctor looked incredibly smug. "We're in Sweden."

"We were in London," she mumbled, looking back out at the forest. "We are in London. You've drugged me, right? This is a trip."

"No!" The Doctor sounded a bit offended, coming up behind her. "Well, it could be, I don't know you. I hope not though, you work in a hospital. But we've left London, this is Sweden! Roughly-" He checked the watch on the inside of his wrist. "900. This is where I tracked its origins to."

"The creature?"

"Yep!"

"You're a liar. I guess I can buy this thing being a ship, you don't fit that in a box without something alien, but time travel just- it's not plausible!"

"Well, I'll prove you wrong! I like proving people wrong. Off we go!" He closed the door behind himself and began walking through the forest.

"Where are you going?"

"Not sure! Just following my nose, are you coming?"

Callie glanced around before deciding she'd be better off following him, and scurrying to catch up.