AN- Oh this chapter was hard, I actually started the next chapter before this one (I rarely write in chronological order, keeping my muse is easier if I skip around to my favorite scenes) so finishing this in time was a challenge, especially because I wasn't really sure what I even wanted to happen. This is definitely an exciting chapter though, so grab a cup of coffee/tea/hot chocolate, curl up by the fire this Christmas Eve, read, enjoy, and review!

Disclaimer: Again, really? I don't own Doctor Who, but tomorrow is Christmas. If anyone would like to give me an amazing Christmas present, please give me all of the rights to Doctor Who and the ability to bring David Tennant back to the show! Also, I don't own Harry Potter. He belongs to my hero, J.K. Rowling of course.

The room that Rose entered was a huge, cylindrical room, about 70 feet in diameter and largely empty. The ceiling rose up above her about 20 feet or so, high enough that she couldn't see anything above the much lower, weaker lights that appeared to be running on emergency power. At the very center of the room was the remains of what appeared to have once been a giant glass case, complete with wiring that had connected it to the power and control panel that was along the wall adjacent to her. Technically the control panel had been behind a glass window, but that was now shattered as well. A bluish liquid was pooling around the bottom of the case from where it had been broken, although Rose remarked to herself that it was more likely something had broken out, and some of the blue liquid was dripping down into the crater that lay between her and the other half of the room, its edges backing up to the walls on her half and the glass case in the middle of the room. Around the lip of the crater and scattered within it were what appeared to be over 30 piles of ash, but as Rose approached one and crouched next to it, she recognized it as the remaining endoskeleton of a roasted robo-santa. Despite everything they'd done to her, in this universe and the other, she couldn't help but feel sorry for their apparently very violent deaths. Oh, and as long as she was taking stock of her feelings for the moment, she also felt scared. Very, very terrified of whatever incredibly powerful creature had done this. She peered over the lip of the crater, into its 15 foot depth, which was just deep enough to keep her from getting a good look at the black shape curled up in the center. Probably whatever creature she was looking for, but until she could get the regular power back on and illuminate it beyond the dingy, dim, greenish emergency lights, she wouldn't know what she was dealing with.

Inching very carefully around the edge of the crater and holding her breath when some of the barely-foot-wide ground crumbled away, Rose eventually made it to the broken control room. She looked at the machines for a moment, trying to take stock of the damage from the blast. Surprisingly, the underlying technology looked fairly sound, and so Rose slid herself under the mainframe computer to fiddle with the wiring. The whole system was pretty simple, and it only took her a few minutes- exactly two she noted with pleasure, confirmed by a glance to her watch- to reconnect it to the emergency generators. She'd picked up on engineering and technology modification quickly while in Torchwood, studying it on her own in-between work and the mandatory family time. She was surprised how well she'd taken to the subject, but considering its usefulness in situations like this, was certainly thankful for her newfound technologically inclined skills.

Rose glanced at the crater once more with her hand on the switch to turn the lights on. She hadn't heard or seen anything, and whatever was in the crater hadn't moved. For all she knew, it was already dead. But there was a dread in the pit of her stomach, the sense that something was coming, so she pushed the switch, and bolted over to the side of the crater as the lights turned on a bright, cheery yellow. Her heart broke when she saw the body. It was Sasha, her dark brown hair strewn around her, covering her petite face and olive-green eyes. Rose looked down in pity, one of the most dedicated, kindest Torchwood agents, and then looked around, still unsure of what caused this. She glanced back at Sasha, her eyes catching movement in the pit. She watched carefully for the barest twitch, honing her vision in to catch the rise and fall of her chest and the flick of Sasha's eyelids beneath her hair, the slight twitch of her lip as she grimaced. She was alive, and Rose needed to help her, so she ignored the almost panicked race of her heart and nauseous unease as she leaned over the edge of the crater and slid down. She turned the com back on and crouched beside Sasha, afraid to move her for fear of injury, just looking her over.

"Found her, no she looks a little battered, but mostly allright. She's unconscious though, I'm going to try to revive her in a moment. No sign of whatever did this to her. It took out the robo-santas though. Maybe just an energy surge from some leftover Torchwood equipment that exploded," Rose said, trying to reassure herself as much as Arkady, though she knew, somehow, even as she said it that she was wrong. She pushed away her worries and turned her attention back to Sasha. She must've fallen in after the explosion, because she never would have survived whatever fiery blast had caused it, and she really didn't look too injured. Some minor scrapes and burns on her exposed hands and arms, and a strange cut on her forehead that looked remarkably like the lightning bolt scar from her favorite book series. Probably from the fall, Rose smiled slightly when she realized how excited Sasha was going to be about having a scar that matched Harry's. She reached out to touch Sasha, but before her hand even touched her, she was met with a painful shock and Sasha's eyes snapped open- except that they were pure white.

"Rose? Don't touch me! You need to get out, I can't… it's… no!" Sasha shrieked as Rose reached out to her. Rose shuddered at her blank, glassy eyes. How was Sasha even seeing her? A little wisp of whitish energy drifted off of Sasha's arm, and then coiled back into her deeply tan skin as Rose watched in horro.

"Sasha what happened? We can help, whatever did this to you we can fix it," Rose broke off, wondering if she was making false promises. She didn't even know what had happened to her friend, and Sasha's face was distraught as she shook her head, brown hair full of dirt and flinging around her face.

"You can't it is me, it's part- inside me I can't control it you need to LEAVE," she said, her voice vibrating with a sort of static echo. Rose crouched beside her, not touching, just whispering softly, trying to reassure her that she was going to be alright. That she wasn't alone.

"What do you mean? Was it," Rose's voice trembled and she swallowed, "did you do this?" Rose looked around at the destruction and still couldn't understand what had happened. Sasha didn't do all this on her own.

"It was trapped, it was dying, I was dying. I didn't want to leave it-me there, here, alone. But when the glass broke it-I was dying and then it was me and now we are I," Sasha broke off, still mumbling to herself, curling into a ball and whispering about darkness, loneliness, and abuse. Rose felt sick, whatever creature Torchwood had left here was inside Sasha somehow, and it was powerful and utterly mad after so long inside a glass case. And now it was controlling, at least partially, Sasha's mind.

"We can help you, but you need to leave Sasha alone, we won't let you die but we can't help if you kill her. Whatever you're doing it's hurting her," Rose said firmly, though a pleading note slipped into her voice as she tried to communicate with whatever it was. Sasha's face was suddenly contorted with pain and fury at the same time. It was unsettling to see on her friend's face, and Rose took a step back.

"You do not see! I am Sasha, my mind, my body. You would take that away? The old Source is dead, but now her mind is mine and there never was an outside mind and my-our-my energy is in this body. We are symbiosis and evolved and one," Sasha sputtered, her words so convoluted Rose could hardly make sense of it. Whatever this was, it wasn't like anything she'd ever seen before. The thing wasn't controlling her, it honestly seemed like their minds had been completely combined. But the combination had obviously driven it mad, and as Rose watched another swirl of energy drifted of Sasha's body like a solar flare before snapping back within. It was then that she realized it might be dangerously out of control over itself. She knew what Torchwood would have her do- take it out now while it was still weak, but Rose took one look at the miserable, tear-streaked face of her friend and knew that she couldn't. Whatever the risk, she had to try to save her.

"Sasha?" she questioned gently, relieved when she nodded her head in recognition. Maybe there was still something left to save. "What did you do to cause this? I am afraid you're going to hurt yourself, okay?" her face got tight and Rose could see the energy swirls drifting out with more purpose. She quickly backtracked and searched for something else to say, "I just want you to focus on your breathing and staying calm and controlling it. That's right, in and out, in and out," she just hoped her hunch was right, and as Sasha breathed in deeply, the surges of energy retreated underneath her skin. A smile even spread across Sasha's face.

"The pain has faded," and Rose shared a grin with Sasha, who looked quite a bit more cheerful, and wondered what she was going to do next- she hadn't thought very far ahead of getting Sasha to calm down and control her symbiotic alien powers or whatever. And then the plan all went to hell as everything fell apart.

"Rose, what did Sasha do? Nothing you've been saying makes any sense, do I need to call in backup? If you need it I can send a containment unit out there, is she secured?" Arkady's voice rang in her ear, and Rose swore. She'd forgotten to turn off her comlink, and Arkady had heard everything. The last thing she wanted was Torchwood coming in to 'secure' Sasha and lock her up- or worse. Rose instinctively knew that whatever had happened to her was not going to be reparable b force and was probably impossible to reverse. She just needed more time to figure out what to do, and hoped that Arkady trusted her as much as she thought he did.

"No, we're fine. I'm going to help her, everything's fine, it's just going to be us alone for a while. Nice and quiet," she said softly, giving Arkady her code for 'everything's okay, don't need any other agents and leave me alone please and thank you' while trying to keep Sasha calm. She turned off the com again, and feeling the hair on the back of her neck rise again looked up to see Sasha's eyes open again and flickering with light, face twisted in fury. Around her swirled tongues of crackling energy, like a cross between lightning and a solar flare. Oh, this was bad, so very, very bad.

"You betray me- he is to send in others- you're capturing me again. Don't put me back in the strange chamber- pulling and pushing my body, my energy fading and dying, twisted- I can see betternow," its tone changed, becoming steadier and taking on wonder. the swirling storm forming around Sasha's body didn't fade however, energy leaking out of her body, then pulling back in. "I am Sasha, what I was is gone. Rose, you were my friend, are you going to lock me back up? Please don't, not again," she pleaded, looking at Rose, reaching out before pulling back, trembling. Rose was scared, but she could sense the pain and fear in her friend, and had to help her.

"No, Sasha, I won't let them take you." She pulled off her weapons belt, and threw it to the side, knowing this was probably an incredibly bad move. But she knew that Sasha wouldn't hurt her, and she needed her to trust her, to calm back down. "See? No weapons. I told him to go away. Do you remember Arkady? He's worried about you. Just breathe, Sasha, it's going to be alright." Sasha gave her a smile, her face relaxing a moment before she suddenly gritted her teeth. Rose winced, sensing Sasha's pain- how she had no idea, but there was no time to swell on it. She could distantly feel the power rolling off of her friend, just barely restrained within the bounds of her body, and she had just enough warning to duck away, curled onto her side as with a final scream Sasha exploded- at least that's what it looked and felt like.

Sasha's body was engulfed in crackling, glowing, pulsing white, and whirling tentacles of energy lashed out around her. There was no way to reach her, Rose could feel Sasha's mind fragmenting under the onslaught of energy. She wasn't doing this at all, she couldn't control it, couldn't stop it, there was nothing to do and no way to save her. There was also no time to grieve her. As another energy tentacle swung past her head, Rose ran for the walls of the pit, grabbed her weapons belt, and hastily scrambled up the side. She was pressed against the wall, the lights flickering between the emergency green and bright white when she heard- somehow, amazingly, above the crackling zapping din and Sasha's weeping and screaming, another door open, across the pit and behind the glass case. Whoever it was, she couldn't see them, between the broken glass, wires, and flickering lights, but Rose just closed her eyes and prayed they'd get out before they got killed too.

"What do we have here, strange energy monster- check." The voice was so familiar, but so soft and barely audible that Rose was sure she was hallucinating. She choked a little bit anyways and opened her eyes, straining to see the shape standing almost 50 feet away. It might be… but with the lights now dimming steadily she couldn't be sure.

"Doctor?" Rose cried out, heart in her throat, hope- she couldn't even describe it. She waited, and waited…

"Is that you Rose?" the form ran up to the edge of the pit and she could see him, in a blue suit instead of a brown coat, but there. How had he even gotten here- never mind that now. He was, and all that separated them was a pit with a raging, mad, out of control energy monster that just happened to be Rose's best friend. Typical. She let out a strangled sound of relief, something between a laugh and a sob. His face lit up, though it was still lined with worry. "Should've know; weird energy surges, screams, you'd be here of course. Jeopardy friendly still, I see." Rose did laugh then, hugging the wall as if it were him. She looked at the wall on either side of her, the floor already crumbling away under the pulsating blasts rolling off of Sasha. There was no way for her to reach him, but at least he was here now, and if anyone could fix this it was him.

"It's my friend, Sasha- that woman down there," Rose pointed and winced as another blast of energy-tendrils whirled out of her, taking out the control room in an explosive display of sparks before receding. The Doctor raised an eyebrow.

"Admirable taste in friends, I see." Rose rolled her eyes, despite the life-or-death situation. G-d it was like they'd never been apart.

"She was sent here by Torchwood, she's an agent too, to check on an energy surge. Turns out this old hholding facility still had something locked up in that, er, glass container and it was dying, and best I can get from what she told me is the creature sort of melded with her. There minds are the same, but it-she can't control her own power. I want to help her, but I don't even know what happened!" Rose called out to him, trying to keep the panic out of her voice. She just wanted to seem strong for him.

The Doctor had already started running his sonic screwdriver- she'd missed that thing so much- over the containment device and was murmuring things she could barely hear- shouldn't be able to hear in fact, not with the distance and the noise, but she could nonetheless. Something about neutral energy, and magnetism, and then he suddenly jumped up excitedly, waving as if to ensure he had her attention before shouting across the pit to her.

"It's a Koricallan energy wyrm! They are a being of living energy, they're peaceful in their home planet but they don't fare very well outside that environment. They're positively charged energy, and their whole planet and atmosphere is positively charged too. Otherwise they wouldn't survive. Here, with all the negatively charged particles, she's been drawing in and pulled towards the energy all around her. It's stretching her out, undoing her own molecular structure, and driving her mad. And she's puling in energy subconsciously to try to make up for the deficit. The wyrm must've been pulled into Sasha's mind by the electrical impulses of her brainwaves, starved after so long in a forcibly neutral containment cell. Now, their energy is so highly entwined, it would be impossible to undo. She's going to keep pulling in energy until she destroys herself. I'm so, so sorry," the Doctor looked at her, pain and loss evident on his face, and Rose knew he was apologizing for more than Sasha's death. But this one, this loss wasn't on him. This one was all her fault, Sasha was under her command after all.

Rose felt tears well up in her eyes. Sasha didn't deserve any of this. She hadn't even wanted to be a field agent, preferring the analytical side of Torchwood. And the alien wasn't even hostile, just trapped in a world that was destroying it, unknowingly latching onto the one thing that could try to save it. It was like her, and Sasha was going to die because of both the alien and her.

"But she was controlling it, she was calm and fine until…" Rose broke off, unable to keep going.

"Her mind was calm enough to contain the electrical fluctuations at first, but once her adrenaline and hormones spiked, the energy slipped out and now it's beyond even her reach." His tone was despondent, and Rose caught a glimpse of the man he had been for the past months, but who knew, really, how long it had been for him. She wondered what had happened to him, and then her attention was drawn back to the pit as Sasha screamed, her voice sending out a blast of energy that made Rose lose her balance and slide violently into the crater to land beside Sasha once more. Holding her head and ignoring the burning in her arm, Rose could hear the Doctor's panicked voice, asking if she was okay, but Rose could only focus on her friend in front of her. Sasha's blank eyes were fixed on her own, and in their swirling depths, Rose could see and feel the regret and pain her friend was feeling. As she sat there, the energy building around them, Rose could hear Sasha's voice in her mind, though her lips didn't move.

I can't control it, Rose you need to leave you're too close. It's going to kill me, and there's nothing you could have done to save me. Please, the next surge will kill us both, you need to move. The voice was reaching a fevered pitch, but Rose's eyes were blinking shut, her head fuzzy, and the energy around her swirling through her mind, making her thoughts fuzzy. There was the sound of rocks tumbling down behind her, and Rose felt strong hands loop around her body, pulling her towards the edge of the crater. She continued to stare at Sasha, unaware of anything else, her vision blackening. She could see a white ball glowing within her friend's chest, feel it burning as if it were her own, and then, as she was pulled up towards the edge of the crater, Sasha gave a last cry I'm sorry Rose! before the white light flashed out into a thousand lightning bolts and Sasha was gone. As the streak of white light struck Rose in the chest, she screamed, the heat boiling in her veins, frying her mind, the distant sensations she had been picking up from Sasha nothing compared to this pain. And then the feel of her limbs faded, and her heart stopped, and all went black.

The Doctor finally succeeded in pulling Rose up over the edge of the crater, and he immediately leaned over her, his hearts beating far too fast as he tried to take stock of the damage. She was badly injured, but how, he wasn't sure. He quickly scanned her with the sonic, and nearly broke into a million pieces at the results. Her cells were dying, every part of her body shutting down as the electricity- stronger than a lightning strike, ran through her and destroyed her. Her heart had stopped. Not now, not after everything. He'd been given another chance, to come here, to find her, the universe couldn't take this away from her. It couldn't take her away. The Doctor turned his sonic onto the electrical pulse setting, charging it up and then sparking her heart with it, willing it to beat on its own again.

"No, don't take her from me, please," he whispered, pumping her chest with his hands, knowing it was futile, as he could feel her cold skin and hear the silence where her heart should have been beating. It had already taken her. They'd found each other, only for him to lose her before he could even tell her, finish that sentence that he'd never gotten to on Bad Wolf Bay, and now he never would be able to. At last, he let his hands slip from her neck, where he was trying to feel a pulse that wasn't there, and he simply fell to the ground beside her, wrapping his arms around her and letting the tears fall into her blonde hair. His pink-and-yellow-human was gone.

AN- Oh I know I'm cruel. *Ducks flying tomatoes and a sonic screwdriver set to self-destruct* Yes, I am doing another cliffhanger, and no it is not to get people to read the next chapter although I won't complain if that's an aftereffect, but as I wrote this, this ending sort of just happened, and I had to cut it off here. Don't worry, there is a next chapter, it's not over, and hopefully I don't take too long to update- should either be tomorrow or the day after. This chapter went through 6 different possible outcomes, and took over 5 hours to write. It is literally the longest chapter I've ever written. (I'm so proud of it.) First, I was just going to do a vague alien, then I came up with the energy monster, then Sasha getting possessed, and finally the one I went with which was the symbiosis combined Energy-Sasha. It was fun to write, until the last few paragraphs. Please just hold on and don't throw things at me until you read next chapter. Give me a chance to redeem myself! Oh and review. Even if it's to tell me you hate me right now.