Tom Richardson stared down at the man that had been laid out in front of him.

Finding these intruders had become an inevitability. Two of his brothers had failed to return from their hunts, and now his infant cousin was also missing. The collection of weaponry that had been found along with them had provided one explanation for this, and it was not hard to imagine what might have transpired on their journey down here.

When his youngest brother had stomped in with blood pouring from a sizeable hole in his shoulder, he had known that they could not be far away.

Deciding they needed to be dealt with personally, he had followed his sibling out to confront them.

Discovering that they had reached as far as their ship had not come as a surprise. But it had been one to find them unresponsive and defenceless at the bottom of the steep hill they had quite clumsily fallen down.

It had taken a lot of convincing to prevent his brother from killing them both right there and then.

"No, Karugon, they might prove useful to us." He reasoned, speaking in his native tongue. "None of their kind has made it down here yet, not willingly at least."

"What would you have us do with them?" Karugon growled back. "They tried to kill me!"

"For one thing our natural form is unsuitable for this world." He replied. "Another is that they might have information we need. Now stop moaning and bring them inside."

Grudgingly, Karugon did as he was told and scooped up both men with ease before following after him.

Though their underground world stretched for miles and had done so for many centuries before their arrival, only a small part of it had been chosen to become their home.

The small network of tunnels and caves just beyond where their ship had landed varied in both size and height. It was this which had determined the purpose each of them now served as, and it was one of the smallest spaces available to them which had been transformed into their medical facility.

What little room there was available had been given over to the large examination table that had been salvaged from their ship.

It was a cold and hard unforgiving slap of metal that had never been used by any of them. Not even their aunt had requested it upon giving birth to her child not so long ago, choosing instead to lie down on the floor next to it.

But it had always been an effective tool whenever a prisoner was taken.

Dropping their latest captives on the ground, Karugon made fast work of removing their bags and armour with his large claws. Sneering at how easily he was able to slice through the material, he held up one of the torn vests so his brother could see it.

"Did they think this was enough to protect them?" He laughed, tossing it aside. "A pathetic race, Kalagan. Why would you elect us to become them?"

But Kalagan did not share his brother's humour.

"Do you think we have much of a choice right now?!" He growled. "We've been down here for months already and are running out of time."

"Yes, brother," Karugon mumbled back. "I just meant that -"

"Just secure them and put all of their weapons down on the table over there."

Karugon nodded and proceed to remove what the two men had been carrying on them.

It was a curious collection and he couldn't resist looking at each of the items in detail. Perhaps he would get to keep one or two of them after they were done. Karugon enjoyed learning about the different species they encountered, even if it was just a method of survival.

There was a large knife and a pair of metal sticks that folded away neatly into small cylinders. But it was the smaller and heavier weapons strapped to the legs of the men that caught his attention the most. They were sat in protective pouches, but pulling them out he saw a handle at one end and a round hole at the other.

There was a curved piece underneath the main body. It was encased within a thin square strip of material that looked to be there to prevent the user from accidentally knocking it against something.

"This is what they used to hurt me." Karugon realised. "This hole bears the same mark as my shoulder."

Kalagan smirked at his brother's ignorance.

"I believe it's called a firearm." He told him. "You were too young to remember our visit to the planet Tririnus. The people there had them too. But something as small as that one won't hurt us. Perhaps they had a larger version and dropped it during their fall."

"I could go and look for it?"

"Later, Karugon. For now, you can do as I've already asked. Secure them now, before they wake up."

Marvelling at the weapon one last time, Karugon reluctantly set it back down on the table and turned his attention back to their prisoners.

"Which one do you want?" He asked. "Are you going to question them both?"

"That depends on which one wakes up first. But he will do for now."

Kalagan pointed at the dark-haired man and watched as Karugon yanked him up and dropped him unceremoniously onto the examination table, strapping him down tightly to it. His sibling then dragged the other over to the cabinet stood against the rear wall where he tied the man's hands around one of its legs with a spare strap he had found in one of the drawers.

"What now?" Karugon questioned once he was done. "How long until they wake?"

"I'm not sure." He replied. "But take everything but the weapons back to the ship. Then come straight back here."

"What about -"

"Don't you dare disturb her with this. Not until I've finished with them." Kalagan ordered. "Understood?"

"Fine, just don't start without me." His brother obliged. "I won't be long."

It was only when Karugon had gone, taking the seized equipment with him, did Kalagan turn back to the table and to the man lying upon it.

Before this, he had only encountered two examples of this planet's inhabitants, one of which he now resembled so perfectly. Even so, it was not difficult to see that this one was physically stronger than his current form was. Braver too if he had come down here of his own free will.

But there was another reason why Kalagan had chosen him over the other to question first.

This species was weak given that they had so easily hurt themselves. The second man, the one tied to the foot of the cabinet. His face was covered in small cuts and bruises, his left eye blackened and swollen amongst a thin trail of blood that was trailing from a gash just above it.

There was a medical covering on his neck too, a tell-tale sign that he had encountered some of their family recently but that he had been fortunate in not quite having his throat torn out.

This was not the case with the first one.

It was very strange indeed that, having fallen down the same incline, the man before him had nothing but dirt and sweat upon his skin. He smelt of blood, and there were tiny dried flakes of it amongst the grime. So either he had gotten the other man's blood on him or…

But surely the lacking of any injuries meant that he had not bled himself?

"Perhaps you are not so weak?" Kalagan mused, smiling. "I can't wait to find out."

Slowly, Peter felt his senses return to him as he fought through the dizzying darkness of unconsciousness. The back of his head was throbbing in sharp, painful bursts and he could hear his own heartbeat pulsing through his ears.

Then he heard three more hearts and knew he wasn't alone.

One had to belong to Stefan, but he could not account for the other two. If the Doctor and Rose had explicitly defied his orders and followed after them then that would make them collectively one heart too short.

Also, he highly doubted that the Time Lord would have come without his companion.

Then the metallic tang of blood wafted up into his nose and Peter knew that his current situation had just gone from bad to worse as he tried to sit up and open his eyes.

He regretted it almost at once.

Even this small amount of movement was impossible. It was all fuzzy and far too bright, his head was swimming so much that he knew he was going to be sick if he tried to carry on any more.

Where was that light coming from? Why was there any kind of lighting down here when the creatures were almost blind and used sound to find their way around?

Groaning in protest, Peter shut his eyes and allowed the darkness to envelop him again.

Karugon's anger towards the two prisoners had wained slightly since his return. Now they were at his and Kalagan's mercy, however, his curiosity and anticipation had spiked. This was especially so when the man laid out on the table had shown signs of waking up.

"He's coming around."

Kalagan had noticed this too and approached the table, standing right next to it so that he would be easily seen. Waiting only a moment longer, he leaned over and spoke.

"Can you hear me?" He asked softly. "Do you understand me?"

A voice that Peter did not recognise was what roused him for a second time. He was conscious enough to register that it was a male tone and English speaking. Were they talking to him? If so he didn't know them and given where they were that was enough to immediately put him on edge.

Opening his eyes again, the face of a ghost swam into view.

"You?" He croaked. "That's..."

He stopped himself only because it wasn't impossible. Tom Richardson might be lying dead in a muddy field, but that did not mean that he could not also be standing here in front of him as he was right now.

A metamorphic race.

That was what the Doctor had called these creatures. It felt like a lifetime ago, but now Peter could at least confirm that one theory had been proven right tonight. The figure stood over him was a carbon copy of the murdered man.

"Who are you? How did you get here?"

Peter wasn't deceived by the gentle tone. He could feel the thick leather straps that were pinning his wrists and ankles down to the table he was laid on. Then, out of the corner of his eye, he caught a glimpse of the creature Stefan had injured. It was stood a few feet away, crouched down on all fours like some overgrown pet.

This was no idle chat. It was an interrogation.

Immediately Peter refused to panic and thought back on his training. UNIT and the British Army had prepared him for this and he could hear the voice of his drill sergeant instructing him even now.

His words were his only weapon and his life was going to depend on what he chose to do with them.

Negotiating with a huge alien creature was not something anyone could ever be prepared for, of course. But Peter also knew the importance of keeping the situation as calm as possible. In other words, he had to rationalise it. Even humanise it to a certain extent.

Then he remembered that Stefan had been with him.

Peter knew that his friend was close by and alive. He could hear his heartbeat even now, but he did not dare to begin to try and look around for him. Doing so now would only give the creatures a source of leverage that could be used against him.

Instead, he stared back at the dead man's face with a cold and calculated glare.

"You first." He told him. "Because I know that you're not Tom Richardson."

"Oh, aren't you clever?" He replied, sounding impressed. "You're not deceived at all, are you?"

"It's hard to be when I know the real one is lying dead in a field with his throat torn out."

"Yes, perhaps I did get a little over-excited. It's been so long since I've hunted, I forgot how little blood is required for us to transform."

Peter absorbed this new information and had noticed that his captor was missing a tooth. It was he who had killed Tom Richardson so violently, so without mercy. All for what, his appearance? That couldn't be the only reason. There was something else going on here, he was sure of it.

"Well, you certainly got enough of his." He quipped. "We found your tooth by the way."

"Is that so? You and your friend, was it?"

Peter watched as the alien circled around to the other side of the table. Turning his head to follow him, Peter was now looking at the back of the cave where a large cabinet was stood.

That was when he saw Stefan.

The corporal was sat slumped up against it with his hands bound behind his back. Unconscious, bloodied and bruised, it told Peter that the severity of their fall had been as bad as it had felt. But he was still breathing, and that was the important thing.

"What do you want?" He hissed in response. "Because if you think -"

"Save your threats." The disguised creature told him. "We have not harmed either of you and do not wish it just yet."

It wasn't hard to miss the hint of hostility in his tone, and Peter responded in kind. Regardless of his current situation, he was here to do a job and he was going to get some answers.

"What about the girl you took, have you hurt her?"

"I was not responsible for that. But I am guessing that is why you are here?"

"Yes, and I want to know if she's still alive." He bit back at him. "Where is she?"

The wounded creature suddenly growled something angrily in a language that Peter did not understand and stomped angrily towards him. But he was swiftly saved, however, when the other held up a finger to stop it from coming any closer.

"My brother is not happy that you attacked him." He explained. "I stopped him from killing you both."

"Do you want me to thank you? When you've killed one innocent person and kidnapped another?"

"Perhaps I am owed your name at least?"

Knowing any information he gave might put any number of lives at risk, Peter hesitated. But then again, his name was of no consequence, was it?

"Lieutenant Peter Argent." He admitted. "What about you, Tom? Who are you really under that human skin?"

"My name is Kalagan. This is my brother, Karugon."

"Well, I can't say it's a pleasure." Peter countered. "Family affair, is it? How many of there are you?"

Kalagan's face twitched at this, and it quickly became apparent that the time for exchanging pleasantries was over. Peter tried not to flinch when he suddenly leaned down over him and drew in a deep, lingering breath.

"Perhaps you know better than I, lieutenant?" The alien questioned. "It is strange. I've seen the female you speak of, and you are nothing like her."

Peter almost dared to laugh at this.

"I can think of a few major differences between me and a girl." He told him. "Do you need me to explain them to you?"

"No," Kalagan replied. "That won't be required."

Without warning, he struck him across the face with the back of his hand.

The blow was not enough to knock him out, but Peter's head spun from the force of it and he could taste blood in his mouth. But he barely had time to register this before Kalagan's hand wrapped itself around his jaw.

There was a small cut on Peter's lip, and it was this that Kalagan seemed to be marvelling at as he gently ran his thumb across it. "Just as I suspected." He mused. "How interesting."

Though the wound itself was tiny and had produced little blood, any trace of it had vanished entirely within seconds of Kalagan lifting his thumb away. It was as though he had never hit Peter in the first place.

"Whatever you're planning," Peter began. "It won't work."

But he already knew from the way Kalagan was smirking down at him that there was nothing he could say or do to prevent what was about to happen. Whatever information the creatures wanted from him, they were willing to do anything to get it.

Even worse, they might have just figured out a way in which they could obtain it.

"How will you stop me, lieutenant?" Kalagan cooed with delight. "Besides, we have yet to find out what it is that you really are. I intend to find this out, of course."

Suddenly Peter was back in front of the Doctor, having the same argument that had put him here in the first place. Why was everyone so interested in finding out about him tonight?

"I don't know what you mean."

"Oh, I think you do." The alien whispered back. "I can smell it on you."

Peter felt the words get stuck in his throat.

These creatures might be blind but it should have been assumed that they had a superb sense of smell. It was essential for hunting down their prey, and there was little doubt in their ability to sniff out even the faintest of scents.

Anger flushed into Peter quite quickly, straining against the straps holding him down.

"I don't care what you want. I'm not telling you anything."

"How brave of you." Kalagan laughed. "Perhaps I should take your shape? But then again, I might be generous and give it to my brother instead?"

"Is that why you're doing this?" Peter asked. "So you pass yourself off as us?"

"It is more than your appearance we take." The alien corrected him. "Much more."

"What do you mean? What else can you possibly get out of drinking someone's blood?"

Though Kalagan's face was human, it had never looked more alien. He was grinning maniacally like a child who wanted to see how wide his mouth could go. His fingers were constantly twitching as though the claws hidden within were itching to be used.

"Our race has a very short lifespan. So we must take what we can from other species. He told him. "Imagine, being on the brink of death only to become reborn again. Able to live for years and even decades more."

"At the price of becoming those same people." Peter rebuked. "You're human now, aren't you?"

"In all but the senses I require to hunt." He confirmed. "Though this body can see far better than I ever could. Even if it is only with the aid of these lights."

So that was why the cave was lit up. These creatures had become other species before and had required aid in seeing their lair once transformed. Peter wondered how many times they had done this already, how many stolen lifetimes they had already lived.

"But you don't just stop at one form, do you?" He accused. "Every time you want an upgrade or a few extra years on the clock, you'll just go out and spill more blood."

Almost every hostile alien he had encountered in his career had the same thing in common. Whatever their intentions had been it was their ambitions which had always pushed them too far, regardless of how justifiable they had made them seem.

An innocent man had still been murdered and his girlfriend had been snatched away. All to fulfil these creature's lustful desire for blood and a life that was beyond their limitations.

"Perhaps you are right to judge us." Kalagan considered. "But speaking of upgrades. Karugon, will this one be sufficient for you?"

Peter's heart skipped a beat as he watched the colossal alien stomp towards him, its drooling mouth parting to reveal its monstrous fangs.

"Get the hell away from me!" He shouted. "Don't you dare!"

Was it going to bite into his throat? Peter didn't want to die that way, just another corpse left behind by this vicious set of brothers. What made it all the worse was that Karugon was going to look like him. That could be disastrous in itself should he try and pass himself off as him.

Forget staying calm and forget all of the training, Peter wanted out of this mess right now. With all of his strength, he pulled against the straps holding him down as the creature's long claws reached out for his skin.

The leather bindings groaned in protest and he could feel the buckle holding them to the table beginning to bend as he fought for freedom. Just a few more seconds and he would have…

It was too late.

Agony shot through Peter like a bolt of lightning as Karugon used a single claw to slice down the length of his arm. Biting back the cry of pain, he felt sick as the alien leaned down and began to feed on his blood, sucking and lapping it up like some kind of horrifying vampire.

Unable to endure it any longer, he passed out into oblivion.