Well, I pretty much slammed the first chapter up without any sort of introduction, so just a few quick notes...

First, thanks to those who reviewed! I appreciate your kind words, and it really did urge me to continue.

Secondly, I don't own any sort of Doctor Who rights etcetera, etcetera...

Thirdly, there's a rating of K+ for the occasional language and possible scary happenings.

That's all for now!

ooOOoo

What he hadn't shared with Martha was that he was still feeling funny in the head. It was the same sensation as a person's ears ringing after being at an excessively volumed concert, but in this case, it was his head that seemed to be ringing. Unfortunately, his TARDIS wasn't going to stop falling apart just because he was feeling sub par, so the Doctor ignored it as he did many such things. He proceeded down what could have been considered a central artery of the ship, a corridor that connected to several others. The room he was searching for was one of half a dozen part laboratory, part storage rooms that existed within the ship's walls. There, he hoped to find the equipment he needed to draw out whatever had infiltrated the TARDIS and contain it.

The Doctor turned a corner and was greeted with the sight of the same black scrawling lines that were creeping along the walls of the console room. "No..." he murmured, staring at the faintly iridescent lines. He hadn't expected it to advance so far so quickly. He picked up his pace and spoke into his communicator.

"Martha, can you hear me?"

ooOOoo

She was so engrossed in keeping an eye on the monitor that she all but yelped when the Doctor's voice came over the two-way. "Loud and clear, Doctor," she answered. "Nearly gave me a heart attack there, you know."

"Yes, well, I'm sorry, but how's the situation there?"

"It's not getting any better," Martha responded. "These...vine...things, they're all over. It's stretched down along the wall almost to the floor now, on all sides of the room. The monitor's flickered a couple times too. To tell you the truth it's a bit creepy in here..." Actually it was a lot creepy, but Martha didn't want to sound completely childish. "How is it on your end?"

"Pretty much the same," he told her, putting more distance between himself and a wall that had an especially dense knot of tendrils. "It's found its way out here, too. Not too many lighting problems yet, but if you're having them there, I'm sure there are a couple torches in one of the cupboards."

"Doctor, this thing...what is it?" her curiosity finally won out over her fear of the answer. Her eyes slid warily from the screen to the marred walls of the console room. The walkie was silent for a moment, and Martha wondered if she shouldn't have let fear be victorious after all. But he continued at last.

"It's a parasite of sorts that can survive in the Vortex. Feeds on several different kinds of energy; basically, whatever it can get. Sentient, but not in the way you and I are sentient. It operates largely on instinct, but it has something of a cognitive awareness. A drive to achieve its goals."

"So is that what it wants, the TARDIS' energy? What exactly is this thing's goal?"

"To take over."

"Take over what?"

"Anything. Everything. It's a ship's parasite. Like barnacles on a sea vessel, only more detrimental and more intelligent. It wants to multiply and be everywhere, but it needs energy to keep growing. And it's using my ship as a smorgasbord." His voice had taken on a hard edge.

"Well, as long as there's nothing to worry about," Martha joked weakly, with a faint laugh. Couldn't they ever have one of those boring, simple days?

"I think the junction's been scrambled here, can you put the monitor in tracking mode? There should be a compass icon along the bottom of the screen somewhere," the Doctor requested.

"I see it," Martha confirmed, and activated the icon. The screen changed from a status display to a map diagram, centered around a small red dot. "Is that you?"

"Yes, there's a homing device in the each of the comm units. I'm facing what you'd call south, for all intents and purposes. Now, two of these corridors eventually go up a level, but one should go down. Can you tell which one? You might have to advance the screen forward a bit."

Martha poured over the display, tracing each corridor forward in turn. She had no idea how the map represented going upstairs or downstairs, but as long as the Doctor's memory served him, she really only needed to find the corridor that was different from the other two. Fortunately, the diagram proved relatively easy to navigate.

"All right, Doctor, if you're facing the triple junction, it's the one farthest left."

"Are you certain?"

"Yeah, the left one goes down, then splits into two."

"And do you a laboratory labeled on there anywhere? You might have to zoom in on a few rooms to see which one it is."

There was a brief interval of silence. "Yeah, I think I see it. Not too far after the triple junction."

"Good work." she could tell he was moving again. "Blimey, it's a lot darker along here."

"Has the power gone?" Martha asked him, glancing briefly at the walls again. The crackling sound was beginning to be a constant noise now. She watched the red dot progress along the corridor on the map.

"I'm not sure if it's the parasite or not . . . I haven't been down here in decades, to tell you the truth."

"Probably needs a good dusting," she quipped. She noticed the dot had stopped.

ooOOoo

The Doctor had indeed paused for a moment to dig the sonic screwdriver out of his pocket, simply for a source of light. He had gotten to a place where there was so little light that even his Gallifreyan eyes couldn't perceive it, and suddenly all the hairs on the back of his neck were standing on end. He switched on the screwdriver, and beheld the source of his unease.

The corridor he stood in now was covered with tendrils. The walls and ceiling were almost completely black with them. Even now they were creeping along the floor toward where he stood, glistening like a puddle of motor oil. He turned to look behind him.

"You there?" Martha's voice brought him back to reality.

"I'm here," he said, stepping away from the advancing tide of tendrils very carefully.

"What is it?" she apparently read his voice. "Have you made it to the lab? What's wrong?"

"I may have to do things a little differently. I think it knows what I've got in mind."

"What? What are you going to do?"

"Yeah, still working on that. . . ." he could sense something heavy in the air, a tension, like a lion waiting to strike. The ivy-like organism was coalescing into one thick entity back down the hall from the direction he'd come, heading straight toward him. His backward steps turned into a trot as he watched it trying to catch up to him. "Martha . . . how near am I to the lab?"

"You should just about be on top of it by now, if I'm reading this right. To your...right, if you're facing the next fork."

The Doctor looked left, since he was turned about now, and all he saw was a writhing mass of black.

"I'm not sure the lab's too accessible anymore, actually. Does one of the next branches take me to a different level again?" He needed to get off this floor.

"Hang on, I'll look."

"The word of the day would be 'quickly,' Martha," the Doctor urged. The united rope of tendrils was weaving toward him still, along the floor. There was a wave of static over the comm, followed by choppy bits of Martha's voice. He shook the walkie and spoke into it once more. "You're cutting out, can you say that again? Make sure you're holding the button down."

"I am--------button down. I----left--goes down another level."

The Doctor angled the sonic screwdriver's blue light upwards. The ceiling was almost as black as the walls. He had a sinking feeling it was the source of their signal degradation. What's more, the mass of it on the floor was picking up speed. Very rapidly picking up speed. He wasn't sure what would happen if he was trapped in a certain part of the corridor or what would happen if he had to touch it. He didn't want to find out.

"Doctor, can---hear me?"

The Doctor turned and flat out ran. "Mostly," he called into the comm. "I need a way out of this part of the TARDIS, Martha. I'm going to head left when I get to the junction, but I can barely see three feet ahead of me, you're going to have to help me a long after that."

"-----breaking up, Doctor."

"Tell me where to go next!" he said very clearly. He could hear the tendrils close on his heels, like a a lot of animals trodding on a lot of twigs. The blasted thing was following him, trying to cut him off from finding anything that might stop it. At least with Martha directing him, a little bit of unforeseeable chance was thrown into the mix.

The Doctor met the fork at last and sprinted down the left branch. The blue flashes of light thrown out by the screwdriver as he ran were enough to at least tell him this hall was not quite so overcome by the parasite. Yet. Martha's transmission was suddenly clear over the communicator.

"Up ahead of you, there's some kind of symbol on the floor, maybe a hatch? Can you see it?"

"No...how close?" He had to get to it before the still-advancing tendrils passed him and covered it over.

"It's close. Really close! Stop!"

He promptly caught his foot on said hatch, still running at full tilt. He thought he heard something crack when he face-planted into the deck, but he couldn't be certain amidst the rest of the noise. The screwdriver and the comm skittered out of his grasp. The Doctor scrabbled for them as fast as he could and flung the hatch open. The black wave of tendrils was scarcely a meter away, and the crackling sound was almost deafening now as they traversed up the walls and onto the ceiling overhead.

The Doctor slid down into the access tunnel and slammed the hatch shut over his head half a moment before it was overtaken. His left shoulder throbbed unpleasantly. He let himself skid down a few rungs and watched the underside of the hatch darken to an oily black. Soon it began to finger out along what was now the ceiling above his head. The light that had still been working in this particular room until now was beginning to flicker. The Doctor put the walkie in his pocket and the screwdriver in his mouth and climbed carefully down the ladder. It was actually quite a drop, from the looks of it. He wasn't sure he knew what this room was even for. Maybe another store room? It was hard to tell in the dimming light.

When his trainers finally connected with the floor, he looked back up, still gripping a rung of the ladder above his head. Then he froze in mid-motion. He had just caught sight of the underside of his forearm where his sleeve pulled back.

After a very long moment, his left hand pulled the screwdriver out of his mouth and pointed its light directly at his right arm. Slowly, very slowly, he inspected his other arm as well. His hearts were pounding, and for a moment, he felt dizzy.

He finally registered Martha's voice shouting at him from the comm in his pocket.

"Doctor? Can you hear me? Doctor!"

"I'm here." He found his voice and answered the comm at last.

"Bloody hell! You scared me to death not answering for so long! Are you all right? Can you see more of that...that thing where you are now?"

"Martha."

"Yes?"

"I think we have a new problem."

The veins running along the underside of both his arms were pitch back clear up to the crook of his elbows.