"Jones," The Doctor addressed, stepping out of the lift, "Answer a question for me. The people inside the command centre say that the Zaralok appeared in a flash of light two days ago, is that right?"
"If you are referring to the shark-like specimen of indeterminate origin, that is correct." The computer confirmed. "At that time period, all other unusual phenomena began as well."
"Great, brilliant." The Doctor tapped the panel. "Did you happen to record anything when that occurred?"
"My sensors recorded several terabytes of information all linked to the burst of light." Jones replied. "I have some interesting seismographs, but nothing useful to the current situation, unfortunately."
The Doctor tilted his head. "Really? Nothing at all? Tell me about the seismographs then."
"Seismographic data is consistent with an object of approximately one-thousand metric tonnes impacting the ocean floor." The computer offered. "Unfortunately, I am as of yet able to formulate a theory on the origin, purpose, or nature of the object."
The Doctor blinked. That really wasn't useful, unless… had any zoo spacecrafts crashed on Earth during this period? No, no. That would only explain the Zaralok, not how Vashta Nerada or a plague got into the sealed environment of Poseidon.
The Time Lord sighed, rubbing his face. "Well, even computers can't have the answers to everything. One more question, though, if you'd please. How do we get to the reactor from here?"
The computer bleeped. "Routes to areas of importance are marked with colour-coded lines on the floor. Follow the blue line to reach your destination. Be advised, power shortages have caused some corridor light fixtures to lose power."
"10-4, Jonesy." The Doctor gratefully tapped the computer's camera. "We'll be back before you know it… Oh, and get your reactor control subroutines on standby, yeah?"
"Understood, Doctor. Safe travels."
The Time Lord turned to his child. "Come along." He said, grasping her hand, hefting her onto his back.
The Doctor, keeping a tight hold on El as he ran so she didn't fall off, followed the blue line as laid out, towards the reactor room, sonicing light panels along the way.
Eventually, they arrived at the corridor leading to the reactor, well-lit, so the Doctor let El down.
"Ah, looks like Jones already opened the airlock for us. Clever girl." The Doctor remarked, walking down the ramp. The room was dark, so the Doctor pointed the screwdriver at the light fixture, holding the button down. "Let there be light." He turned to El. "That's God. I was quoting God."
El blinked. "Who's that?"
"On a good day, one of my heroes. On most others, the man I hate most in all the universe." The Doctor replied. "But never mind Rassilon, let's get to work."
"I have a question." El spoke up as they walked farther in. "The TARDIS is a living thing, so is she going to be alright?"
"She'll be fine." The Doctor replied, easing her fears. "That part of the base was sealed off, and even if it wasn't, the Vashta Nerada only consume flesh. They don't eat anything else." He explained, fiddling with the controls on the lower reactor.
El nodded and took a look around the room. She gasped, seeing a figure in a diving suit standing across the way, back turned to the two. "Dad, look. Someone's down here."
"Ah!" The Doctor looked up, addressing the diver. "Hello, sailor!"
The diver stiffened and began to shakily turn around. The moment they got a good look at the clear visor, the two gasped.
There was no face… just a skull shrouded in shadow.
"Dad…" El asked, horrified. "What's happened to them?"
"The Vashta Nerada got them." The Doctor answered. "It's just the swarm moving the suit now."
Something clanged behind them, and the Doctor whipped around, as another consumed diver got up from the floor.
"The ladder!" The Doctor pointed.
"Let me-"
"They're a swarm in a suit, you can't harm them!" The Doctor replied, pushing the girl ahead of him. "Delay, maybe, but they'll get back up! So, run, and whatever you do, don't touch them and don't let them touch you!"
The Doctor ushered El up the ladder, and scrambled up after her, as the animated suit walked into the ladder, banging against the wall.
"Um… what's it doing?" El asked, looking through the grated floor.
"The swarm is coordinated enough to move the legs to walk, but not much else." The Doctor answered. "We'll be safe up here… though that's not saying much."
"Why?" El looked back up to the Doctor.
"Well, we came down here to start the reactor… and the controls are on the bottom." The Doctor replied.
"The bottom…" El narrowed her eyes. "Walk me through it. Can do it from here."
"El, it's nuclear physics, not flying the TARDIS." The Doctor replied. "Why, the only thing we can do up here is control the lights. The lights… the lights!" The Doctor suddenly shouted, running down the catwalk, to a light panel. "Aha, bingo!"
"What?" El inquired.
"The Vashta Nerada thrive in darkness because they have to." The Doctor answered, fiddling with the panel. "They're small enough that even bright enough artificial light can vaporize them. Now, the lights in the corridors are dim enough to where they can survive in them, but if I focused all the extra juice I could into one light…"
A light in an alcove below switched on, lighting up as bright as daylight.
"I could get a light bright enough to burn the swarm out of the suits." The Doctor finished, turning to El. "You can't kill them… but do you think you can push them into the light."
El nodded, and looked down, eyes narrowing on the animated suits, stumbling around, blindly trying to find their prey.
With a tilt of her head, both suits sent flying into the alcove, spasming as the swarms in control of each were burned out, before the suits collapsed, empty.
"Heh heh, El, we did it." The Doctor smiled proudly, vaulting over the railing to the level below, as El gently floated herself down behind him. "Now, let's see…" The Doctor peered closer to one of the suits. "Lookie here," The Doctor pulled out a small computer chip, a tiny LED screen on it, "Environment status chip."
El looked to the Doctor for an elaboration.
"These aren't just diving suits. They're Hazardous Environment Suits. TM." The Doctor explained. "Filled with an array of sensors, medical equipment, and all sorts of other useful gizmos. For when survival in any environment is absolute priority." The Doctor held the chip up between his fingers. "In the event of operator death, this chip records the cause so people know what precautions to take when handling the body. And look," He pointed to a symbol on the chip, and then the symbol on the reactor.
El looked to the machine in the center of the room and took a fearful step back from it.
"Don't worry, it wasn't from the reactor radiation." The Doctor replied. "Otherwise I would've felt it the moment we entered the room. And besides, I don't think Jones would've let us get radiation poisoning. This was something else…"
"So the… radio… stuff killed them first and then the swarm got them." El shuddered. "Can we please get the lights back working, dad?"
"Sure thing." The Doctor put the chip in his pocket, before walking back around to the reactor control terminal. "Let me just get it started…"
El frowned, looking at the enormous machine in the center. "What is this thing, anyway?"
"Well, you know how trains burn coal to heat up water to turn their wheels?" The Doctor asked in response.
El nodded.
"Same basic principle." The Doctor replied. "Except it's using a much stronger fuel source, that just so happens to cause cancer if you're not careful."
Turbines began to hum loudly below the room as the reactor engaged, the lights going back to full strength. "And let me hand control over to Jones… Bingo. Right," The Time Lord clapped his hands, "Let's head back to Jones and see what we can get off this."
The Doctor took El's hand as he looked at the environment status chip. Radiation strong enough to kill someone wearing a fully-sealed Hazard Suit…
That didn't bode well.
"'Ello, Jones, me old mucker." The Doctor greeted, walking up to one of the sides of Jones's computer bank. "Can you have a butchers at this for me?" He asked, inserting the chip into a slot on the side.
"Certainly, Doctor." The computer replied. "It is an environment status chip, standard equipment of all Mark IV Hazardous Environment Suits."
"Um, yes, already worked that out." The Time Lord clasped his hands. "The chip says the suit's wearer died of radiation poisoning, but the suit was sealed, and it won't say what type of radiation. Can you maybe tell me?"
"…I cannot." Jones reluctantly replied.
"Why not?" The Time Lord raised an eyebrow.
"It is not a form of radiation in my databanks." The computer answered. "Strange. Included in my databanks are identifiers for every known type of radiation in existence. Perhaps my sensors are malfunctioning."
"No, your sensors are working perfectly…" The Doctor considered. "You can't identify it because it's alien."
"Alien?"
"Yes." The Doctor began typing something into the keyboard on the side of the computer bank. "I'm writing a program which will allow you to register it. I want you to take a look back through your logs and tell me if it has something to do with the flash of light you picked up two days ago."
"…Complete." The computer reported. "How did you know?"
"I had a very strong feeling." The Doctor answered. "El," He turned to her, "We have to tell the others." He said, leading her back into the lift.
The pieces were falling into place.
"Oswald!" Dana came striding excitedly into the life pod bay. "The Doctor thinks he can synthesize a cure for the sickness!"
The Time Lord bounced on his heels, hands clasped behind his back. "Yes, as it turns out, not a plague. Vortron radiation. No, you wouldn't have heard of it." The Doctor told Oswald the moment his lips parted. "But regardless, I can cure it. Poseidon has everything I need. Brine oil, sea sprouts, a little bit of sticky mushrooms…"
Oswald looked incredulous. "Are you serious!?"
"You might use brine oil to keep your machines going, but," The Doctor held up a finger, "It's full of iodine. Just the thing I need."
"They need the access codes to get into the agricultural sectors." Dana explained.
"And, by the way, I thought I told you," The Doctor pointed, "Putting your people in those life pods will only get them killed."
"So I just twiddle my thumbs while you mess around with some of the worst alternative medicine I've heard since essential oils?" Oswald demanded in response.
The Time Lord recoiled. "Okay… no need to get so snippy about it…"
El crossed her arms, glaring. "Listen to my dad. He looks stupid-" "HEY!" "-but he knows what he's talking about."
"And let you go mushroom picking?" Oswald retorted. "So you can get eaten by those things as well? No way! Enough people have died already, no more, Doctor! It's too dangerous, these pods are our only chance. Now… this is a restricted area. So get out!"
El opened her mouth to argue back, but the Doctor just gently grabbed her shoulder, shaking his head.
"Oswald is a good man." Dana tried to defend as they walked back. "It's just… he's not really used to command situations, and so many have already died. The stress would weigh on anyone. He's just trying to do what he thinks is right."
"But we need those codes." El replied.
"Don't worry, El." The Doctor told her. "There's always Plan B. El and I walked through some storerooms on the way here with all the ingredients we need already inside." The Time Lord recalled.
"Are you sure?" Dana asked.
"Absolutely." The Doctor replied. "You get the sickbay ready, we'll be back with those ingredients in a jiffy."
The woman nodded and broke off from the two as they began to walk through the main hall of the command centre.
"Dad…" El looked around at the place, practically smothered in Christmas decorations. "I meant to ask earlier, but… what is Chris-mass?"
"Christmas." The Doctor smiled. "My favorite holiday on the planet Earth." He checked his watch. "After this, there are just a few more things I want to do, and then we can go back to Sarah Jane's, and have a proper Christmas with her, Clyde, Rani, Luke, and everybody else who I knew on Earth in that time, what do you say?"
"…can Will come?" El asked, as they stepped into the lift.
The Doctor glanced at her. "You know you only knew him in the dream, right?" He asked, not trying to be mean or crush her dreams, but trying to remind her that while she knew Will for ten years in the dream world, it didn't necessarily happen in reality. "The only time Will ever came close to meeting you for real was when I threw him back through the portal."
"I know." El said as the lift moved down. "But… I miss him. The him I knew. …I want to try."
"…Maybe we can give it a shot." The Doctor said as the lift stopped. "You do need some friends closer to your own age… Who knows, if he has friends, maybe you can meet them too. Expand your circle of friends."
El made a little hm and looked ahead.
"…What is friend?"
The Doctor looked to her, as they walked through the corridors of Poseidon, towards the areas where he knew the materials he needed were. "I never told you?"
El shook her head.
"Well, a friend is someone you know, who you keep in touch with a lot." The Doctor answered, grabbing a sea sprout. "Someone who's close to you but not someone you love like a boyfriend or girlfriend. Like… Sarah Jane." The Doctor listed, grabbing a sticky mushroom.
"But, she's my aunt."
"No, I meant Sarah Jane in relation to me." The Doctor elaborated, scooping some brine oil onto a small jar. "She's… almost like an older sister to me? Except we're not related, and I'm actually way older than she is, so we're close friends."
"Oh." El nodded.
"Don't worry, I'm sure you'll get some friends of your own someday." The Doctor told her. "This should be everything. Let's get back to Dana."
