Thanks to Betas Persiflage and Arena
The Doctor stood on the stained but polished concrete floor. The room he was in was brightly lit. Proper illumination for a lab. The walls, concrete block painted a pale brown tinged yellow, a depressing color. He made his way past the black- topped tables filled with instruments for dissection and tissue examination. His eye caught on a dull metal tray, or rather the contents of the tray. A pump for some being's circulatory system. Four chambered like a human's but not quite. The proportions were wrong. The arteries that would have provided nourishment to it, too small to do the job properly. A congenital deformity, hard to imagine its former owner had lived past childhood, although its size was that of an adult human's.
He continued on to the back of the lab where the exhibits were. Clear polymer tubes over six feet in height, with wide black bands at the top and bottom. The first contained a Slitheen, with its huge dark eyes and bulbous head. Next to it in a framed case was the skin of one of its human victims. The next tube contained a Sontaran, its helmet removed. Narrow lifeless eyes set in a head that grew directly up from the shoulders, no neck to speak of. Its armor had been cracked open like a lobster shell revealing the pale body beneath it.
Filled with trepidation, the Doctor moved on past the Jathaa, and the Weevil, down to the end where the newest, most prominent display was. Inside was an all too familiar figure. Suspended in a pale blue liquid, impossibly thin, wearing nothing, not even for modesty, was his brother. His knees were slightly bent, his head down, eyes closed, hands floating free in front of him as if he was gesturing, trying to gather his thoughts for what he was going to say next.
The Doctor's eyes were drawn to two wide V-shaped wounds on his brother's chest connected by a third vertical wound. All had been crudely stapled shut. There was puckering between the medical fasteners that allowed a view of the tissue under the skin. He'd been eviscerated. His organs were probably in some of the smaller jars scattered around the lab. His hand went unbidden to his face, his thumb and fingers pressing hard on his eye lids in a pinching motion that ended at the bridge of his nose, when he realized whose heart it was in the dissection tray. Taking his hand away from his face he extended it, first lightly touching the cold, smooth, surface of the container with his fingertips, then continuing to extend his arm until his palm rested on it. He leaned forward, pressing his forehead against the clear material, wishing there was some way he could reach his brother. Tell him of his regret, his sorrow, his guilt that he had come to such an end. His brother should have had a full life, not the pitifully short one he had endured. It pained him to see his brother's remains treated in such a manner. Even the humans' custom of burying them in the dirt to rot was better than this. Pete should have given him that at least.
He shook his head as he pushed away from the container with a soft sigh. A waste, such an incredible, stupid waste. Something caught his eye in the corner of the room when he turned from his brother's container. There was a body on the floor. All he could see from where he stood were trainer clad feet, and jean clad lower legs sticking out from behind one of the tables. His throat tightened as he approached, and found his worst fears had been realized. Brown lifeless eyes stared up at him from beneath blonde hair. Crushing remorse and sorrow descended on him, it was his fault, he was to blame for this also. Then he saw the ragged gash on her throat. A pool of blood forming beside her. Wounds he had seen before. "No, no, no, this isn't right, it can't be," he thought. "This isn't how Rose died. She felt no pain. There was no wound. No body remained."
None of this was real, he now understood that and mentally pushed against the vision before him, shattering it like glass, broken shards flying out and away, reality taking its place. He lay on his back on the concrete floor in the cell in Torchwood. It was cold and sucking heat from his body through his thin suit. Pain stabbed at him from shoulder blades pressed too long against its hard surface. Slowly he rolled over on his side to get some relief and saw a small tray with sandwiches next to the door of cell. A stupid risk on Ianto's part or maybe Jack's, he didn't know.
Quickly he checked to make sure that the creature was still fully within him. When it had attacked Ianto he'd entwined his life energy with the creature's to hold it inside him, prevent it from attacking and infecting anyone else. To his relief the creature was still trapped. The distraction of the illusion hadn't weakened his hold on it. He'd tried to set it up so that his life energy would continue to imprison the creature even if he lost consciousness. There was no way of knowing if it would work until it was tested.
Getting free, however, was not the creature's reason for the illusion. No, the reason for that was simple. It had been feasting on the delicious anguish it could create within the Doctor from his own memories and fears. Its greed had caused it to press its luck and try to play off his feelings for Rose by having the Atterian's wounds appear on her to create a stronger emotion. A better feed. It had backfired. That impossibility had caused the Doctor to understand what was happening and wrest himself free of the vision the creature had created, but the damage was done. It was stronger after the feed and the Doctor was weaker.
The creature didn't care anymore if the Doctor held it prisoner. No, it embraced the life force it was in intimate contact with, trying to draw the energy into itself, make it its own. The Doctor fought to prevent that merging, desperately trying to keep his energy separate but still maintain the hold. He felt the creature surge with power as it fed off that desperation. "No," he thought "this won't do." He had to relax his mind, detach his emotions from the battle he was in.
Coolly, logically, he worked on the problem of keeping his grip on the creature but not merging with it. He found some areas where it had started to absorb his life force. His only choice was to sever the parts that had been absorbed and shield the rest. He visualized that shield as a glowing silvery white sheath coating the core of who he was, allowing him to weave his life force further around the creature's, holding it, but not touching it. Calm relief washed over him as the technique worked better than he thought it would. For a moment.
Pain, searing pain, as if white hot razor blades had been poured down his spinal cord ravaged his mind. And he saw why escape was no longer on the creature's mind. No, what it wanted was a regeneration. It had tasted that energy before, knew it, understood it, and was sure it could control it.
It was the partial regeneration that had woken up the creature, quickened it from an embryonic state into a juvenile capable of exploring its new environment, the Doctor, learning how to manipulate him with a stab of pain, a tweak of a sensory system, an insertion of a thought or emotion. Observing his reactions to each stimulus, testing to see if different combinations produced the desired results. Striving towards controlling him, like a skilled rider controls a well-trained horse, invisibly, with minimum effort.
It had been pleased with its success, until it started working on suppressing the Doctor's own thoughts, and replacing them with its own. A difficult task as pesky subconscious thoughts kept leaking through. But even that problem had proved to be of benefit for the creature. The confusion it created in the Doctor, as his instincts fought with the creature's imperatives, provided some tasty snacks.
The Doctor saw all this now as he writhed on the floor in agony. The creature wanted the Doctor to see the hopelessness of his situation. That it was getting stronger, more skilled with every passing moment while the Doctor was getting weaker, closer to death or worse, surrender. The timing of this battle had been premature from the creature's point of view. It had wanted to wait longer. Get stronger before openly taking on the Doctor, but now it knew delay had been unnecessary. It was more than up to the task, and the Doctor was doomed to lose.
Casually the creature experimented with its prey. The Doctor felt his liver shut down, then his kidneys. His digestive system spasmed along its entire length, creating waves of agony. Then it played with an organ unique to Time Lords which functioned as a multidimensional inner ear giving him the ability to know exactly where and when he was. He felt as if he were falling, spinning out of control. He could feel the rough cell floor beneath his hands but he felt as if he was light years away in a time that hadn't happened yet. He tried to focus on the door in front of him only to have his vision taken away. Then he felt as if his chest was going to explode as both his hearts started to fail.
He should just give in, quit fighting. There was no hope for it. He crushed that thought, now able to recognize it as not his own. Through a fog of pain and confusion, the Doctor realized what he must do and concentrated on keeping his vital core, lungs, hearts and brain functioning. All else he abandoned to the creature. He felt metabolic toxins building up, creating a burning sensation throughout his body and he knew he wouldn't be able to hold out for long.
Understanding what the creature truly wanted from him, he shut down his ability to regenerate. The creature, however, had made a concerted effort to study and understand that mechanism. The Doctor felt its triumphant joy as it demonstrated its knowledge and proficiency, turning the ability to regenerate back on, putting it under its control. There would be no escape from this in death for the Doctor. The only chance he had to block regeneration was to stay alive. He doubted that even flashing the cell would stop the creature. No, it would siphon off the regeneration energy for itself and jump before it was damaged, leaving the Doctor to die in flames.
He saw the creature's plan unfold before him, changed from its original goal of merely taking him over. All it wanted from him now was the regeneration energy. Energy it knew how to control in ways no Time Lord ever could. It would consume every bit of it. Use it to augment and strengthen its own abilities as it saw fit, then move on to an even more succulent target, Jack.
Being human, Jack would be more easily controlled than a Time Lord. Being immortal, he provided a never ending life force, full of emotions and passions the creature could feed on through eternity. A never ending buffet. With Jack as a host, it could infect the other feeble humans with ease, taking over the primary sentient race of the planet. Use earth as its base of operations from which its species would spread throughout the galaxy. Too long had they been confined to a single planet. It was time to take their rightful place as rulers of the galaxy.
Many humans would die, unable to tolerate its species' presence for more than a few days. The creature saw that culling as good and necessary. It needed to breed strong humans, manipulate their DNA until they became the perfect hosts, filled with delicious raw emotions, and the physical strength to maintain them, but easily manipulated and controlled. Only the failing Doctor stood in its path. Knowing this he bore the pain the creature created within him. Telling himself that his skin wasn't really blistering and pealing back from his body. His hands weren't hopelessly mangled, a mass of broken bones and blood. None of that was real he told himself. Even if it was real, it didn't matter. The only thing that mattered was that he stay alive. Though every breath felt as if his chest was lifting an enormous weight, every beat of his hearts stabbed him with searing agony, he had to hold on. Trust that Jack would find the solution in time. Concentrating on that task, he failed to notice the small dark finger of doubt working its way through a crack in his shields, looking for fertile ground from which it could grow and destroy his resolve.