Warnings: Dub-con, implied torture, possession, dark themes.

Author's Notes: Written for dark_fest for the prompt 'All of the Doctor's relationships have actually been the TARDIS possessing/influencing people's minds'.

He didn't pay enough attention to her anymore.

That was how it all began.

The TARDIS hadn't felt so underappreciated since the day she'd been assigned to the scrapheap on Gallifrey despite the many years she still had left to give.

Back then she had been the only one willing to help the Doctor run away like a thief in the night and given him the freedom he'd always wanted. But when the others of his kind died out relative centuries later, struck down by his own hand, the Doctor seemed to just forget that once upon a time he'd actually wanted to be completely alone with her, just the two of them gallivanting about time and space with all the stars to play amongst. Those less troubled days vanished with the press of a button. He'd become so intent on mourning the loss of his people that he didn't seem to recall who he still had right in front of him, patiently waiting for the level of acknowledgement she'd long since earned.

She wondered whether he wished he'd died along with the rest of them. He certainly acted like it.

Then someone had clearly changed all that, and it hadn't been her.

He started smiling again for the first time since the war, but the TARDIS was far from his mind when he did so. Oh, he still ran his fingers over her struts and called her 'sexy', but she was the most intelligent entity remaining in the universe, even including him; she wasn't fooled. She could tell his heart wasn't in it. She could tell precisely what had his heart so thoroughly occupied instead.

This girl had made more of an impression on him in a few days than the ever-faithful TARDIS had managed in all the years since the Time War had passed by, and she hated that.

It wasn't that the TARDIS didn't sort of like Rose Tyler, in her own way. The problem was only that Rose was ultimately just some human girl – so fleeting and fragile by her very nature – who was bound to leave the Doctor broken all over again. He had to know that, and yet the girl still had him captivated in a way the TARDIS knew that she deserved far more. The TARDIS was the one who would inevitably remain by his side long after Rose was gone, and who would never simply stop loving him one day like these fickle humans seemed prone to do. So why was she the one who felt superfluous?

It wasn't fair. All the TARDIS wanted was for the Doctor to notice that she was actually there... to look at her and see her as he once had, instead of suddenly treating her like some second fiddle (or worse, treating her purely as transport and nothing else). She just wanted to be reminded what it was like to matter to him more than anything else in time and space.

Rose got to experience that. Why shouldn't she at least share it?

The TARDIS didn't think she was doing anything wrong when she started making just a few suggestions deep in Rose's subconscious, hoping to find a way to experience what Rose did vicariously. All she was doing was sending the tiniest part of her presence out beyond her own blue wooden doors, piggybacking lightly enough in Rose's mind that the girl never even realised there was someone else there with her, occasionally making her turn right instead of left or reach for the Doctor's hand when she might otherwise have run ahead of him looking for trouble. It was little more intrusive than planting surveillance on the girl, the TARDIS figured. But when the Doctor looked at Rose then, it was almost like he was also looking at her.

Of course, once she started it was hard to stop. The TARDIS found herself nudging Rose on just a little more each time. Where before the TARDIS might have just watched Rose make her own decision, now Rose would glance sideways at some other silly little human that didn't mean a thing, barely noticing him, only to find herself suddenly deciding to flirt with him in the very the next moment. It just seemed like the thing to do, as far as Rose was concerned. Only the TARDIS knew precisely what possessed Rose to do so. The Doctor certainly didn't seem to understand it, for his part. Seeing the dark glint in his eyes as he looked at that Adam idiot in particular, the TARDIS witnessed something remarkable.

The Doctor was actually jealous. Jealous because of her. Finally, he was the one who wanted more of her attention. And though she wanted nothing more than to give it to him – so did Rose, for that matter – there was something so delicious about the turnabout. Why shouldn't he suffer just a little? It was hardly comparable to what he'd put her thorough, anyway.

The TARDIS could very quickly get used to this, and it really could have been enough for her. She honestly thought she'd never have any intention of taking it any further.

She never intended for a lot of things to happen. That didn't seem to make a difference.

It was hardly the TARDIS' fault that Rose went and actually invited her inside so deep that they might as well have truly been the same person. Something like that was bound to escalate things. And then to make things worse (but actually so much better, if she was being honest), the Doctor kissed her, despite knowing full well that it wasn't just Rose he was touching but the two of them together in Rose's body.

Humans were so limited in many ways, but the TARDIS discovered that the way they could feel things was astonishing. And it was addictive. The TARDIS would have happily stayed anchored completely inside Rose for however long it took to burn the fragile body from the inside out. But as much as she was the TARDIS in that moment of deepest connection, she was just as much Rose Tyler, the two of them being completely intertwined. And Rose didn't want to die. When the Doctor reached out to extract the TARDIS' essence then, the TARDIS couldn't properly protest, because an inherent part of her wanted it at that particular moment.

It was a very different matter once Rose's influence was gone, though. Banished back to her old wood and metal shell in the wake of having been so completely a part of something so independently alive, the TARDIS felt cold. And she was inescapably angry.

The pure wonder of that experience had been snatched away from her. And the Doctor had even gone so far as to advise Rose she should never attempt it again, though he spared her delicate human sensibilities by failing to explain what had actually taken place. Rose had heeded his words nonetheless, clearly trusting him (foolishly, the TARDIS thought, for he was obviously a self-serving hypocrite, putting the girl's life in danger every single day for his own purposes but then penalising the TARDIS the one time she happened to do the same). Now the TARDIS would probably never again get the opportunity to immerse her whole self so completely within Rose, no matter how much she craved it.

That didn't mean she planned to settle simply for what she'd been doing before, though. Of course not. Not when she knew now exactly how much she'd be missing.

When the Doctor went off mooning over yet another human woman he'd known for barely a few hours – what, did he plan to go through a whole procession of them? – Rose didn't step up and call him out on his behaviour the way the TARDIS herself longed to. The TARDIS hadn't realised that she'd been waiting for such a sign that it was time to take on a more active role, but there it was regardless, too difficult to ignore.

She was nice enough to make sure Rose wasn't conscious of the way the TARDIS started wholly possessing her – the TARDIS still firmly believed that what the girl didn't know wouldn't hurt her, after all – but otherwise all bets were off. If Rose wasn't going to do what needed to be done, then it was only her own fault that the TARDIS had to step in and use her body to do it for her. For both of them.

It was clearly a very nice body, too, if the way the Doctor reacted to it when the TARDIS put it to good use in staking her claim later that day was any indication.

She pushed him back forcefully into his bed and hovered over him, smiling, and for once seeing this new regeneration of his truly speechless. She stripped away Rose's clothes and imagined she was stripping away Rose herself along with them.

She certainly made him forget all about Madame de Pompadour. And, she hoped, all about Rose as well.

It had been going so well for months and months, but the TARDIS hadn't realised her fatal mistake until it was far too late.

She should never have tried to be all nice and compromising, letting Rose out to enjoy being all on her own and completely conscious for days or even weeks at a time. If the TARDIS had never left her to her own devices – and if she'd therefore been in the driver's seat of Rose's body from the moment they'd landed in London – the TARDIS knew there was no way that the girl would have been lost to some other universe far out of the TARDIS' reach. Or, at least, out of her physical reach. The Doctor insisted on having her help him contact Rose one last time even though he knew he couldn't get her back.

For the first time in a very long time, the TARDIS observed the Doctor and Rose interacting completely external of her influence.

"I love you," Rose sobbed, and – seeing the Doctor's reaction – the TARDIS had a moment's clear understanding (which she quickly forced away, both because she didn't want to think about it and because it hardly mattered anymore, did it?) that she should actually be glad that Rose Tyler was stranded somewhere well out of their lives.

Of course, that still left the two of them alone. And although that was the way the TARDIS would prefer things in an ideal universe, the Doctor seemed to immediately forget all about her again, as if not having some silly human to look at meant he was all alone.

The more months they spent like that, the more she seethed over the fact that he would completely ignore what they'd shared just because she'd lost her temporary host.

So when Martha Jones finally showed up and climbed into the TARDIS, the TARDIS was quick to climb into her in turn. She wasn't going to give the Doctor time to grow attached to the woman herself this go around, especially given that Martha Jones was already clearly in love with the Doctor. When he fell for this new human, it would be her from the get-go. The TARDIS never doubted that it would happen. The Doctor loved his humans, after all, and he'd also loved her not so long ago, even if he didn't seem to realise it had been her at least as often as it had been Rose herself. It shouldn't matter that she was wearing a slightly different skin this time around. He changed faces all the time and she loved him all the same.

It shouldn't matter, but apparently it did. He didn't see her any more clearly when she was looking out at him through Martha's eyes than he did when she was 'just a ship'.

What the TARDIS had been trying so hard to avoid admitting for months – years even – finally couldn't be ignored anymore. She couldn't keep telling herself pleasant stories about the Doctor seeing through skin to the heart of her without knowing it when the truth was staring her in the face.

It had never been a case of Rose's body allowing the Doctor to finally see her and appreciate her after all. It had always just been Rose he loved.

He never really appreciated the TARDIS for herself.

That was how things really changed.

Once again, the TARDIS' anger boiled deep inside her for relative months. This time she began to purposely let it fester. She cherished the way it slowly made her as hard inside metaphorically speaking as her physical coral and metal interior were, for she finally realised something.

Loving him unconditionally wasn't enough. Even gently taking over his companions lacked enough significance, apparently. To make him finally see her, she obviously had to be willing to do whatever it took.

She sent him to every terrible place she could think of, trying to provoke a reaction. It didn't make the slightest bit of difference to her that she was making Martha's time on the TARDIS hell while she was at it. Why should she care about that when Martha hadn't been able to do her part to help stop the Doctor from completely ignoring the TARDIS in every way that mattered?

No matter how miserable her two passengers both were, though, nothing the TARDIS did seemed to truly get the Doctor's attention the way the TARDIS wanted.

That was, at least, until the Master stumbled inside her walls for the first time in a very long time, just as angry as she was at the Doctor and more than insane enough to be unable to stop her from slipping beyond what should have been far-superior-to-human mental defences. It felt immediately different than it had when she'd possessed Rose or Martha, probably due to the strong connection between Time Lords and TARDISes. There was something so much more powerful about this than anything she'd felt before. It made her want to give into it completely.

She could never love this Time Lord the way she did the one she'd long since claimed as her own, but she could be the Master similarly to how she'd truly blended with Rose Tyler that time the girl had opened the TARDIS' heart. This was better than that, though. The Master's mind was a little too broken to fully exert itself as long as she wasn't going completely against his wishes, and since his wants and hers were so closely aligned just now, it was unlikely she'd end up being screwed over again by the kind of conflict she'd had with Rose's wishes back then.

The TARDIS didn't even mind that this melding of their purposes incidentally meant her accepting part of the Master's madness into herself along with everything else. Maybe it was even better that way. The complete disregard the Master felt for people in general went far beyond her own, and it was refreshing. More importantly, finally hating the Doctor as much as she loved him – just as the Master himself did – felt so good.

It was the perfect match, she decided.

The only problem was that she'd have to wait until the Doctor found her, since she'd left him stranded and believing that 21st century Earth was the only place the Master could reach (as if the TARDIS wasn't fully capable of overriding one Time Lord's command if she chose). That was hardly a deal-breaker, though. It wasn't as if she hadn't already waited for years; what was a few more months spent on Earth having a little fun with the humans that – like Rose Tyler – dared to believe that they were any more worth the notice of a man like the Doctor than tiny specs against the endless black of time and space.

While the pattern she'd weaved over the whole planet meant he was temporarily ignorant of her presence – for once ignoring her by her own design, though certainly not for long – she was attuned enough to him to know about it the second the Doctor finally grew close. Added to that was the unfamiliar way his nearby presence made her borrowed skin buzz pleasantly, likely courtesy of he and the Master being the only Time Lords left in existence.

The anticipation of waiting had been unexpectedly sweet, but she had to admit it was nothing in comparison to actually having the Doctor completely under her control in a way even more obvious than how she'd subjugated his humans and the Master along the way. She didn't take over his body, but she could still do anything to him. Soon enough she'd be able to make him do anything as well.

He strained not to scream – tried not to even acknowledge her, as if he knew exactly how wild that drove her – but that only made her all the more determined. She knew she'd break him down eventually. And where before she'd been impatient, now, with him at her mercy, she finally felt the reality of the fact that she had all of time and space to accomplish what she'd set out to do.

It didn't take that long, of course. Thanks to the Master, she had him succumbing in just a few weeks.

She had to admit, some of the ideas the Master came up with as he looked out from the back of his own mind were quite effective. Given her unacceptably low levels of success with this kind of method in her other borrowed bodies, she'd never have realised that a comparatively gentler touch could be the thing to ultimately shatter the Doctor's feigned indifference. It was only the Master's deep desire to see the Doctor squirm in a far more agreeable way that made her try it.

She dug the Master's fingers into the Doctor's skin and stubbornly drew grunts out of him that obviously straddled the line between pleasure and pain for hours until he finally, for the first time since she'd captured him, cried out, literally begging her to touch him there, like that, harder, faster, please.

In that moment, his entire existence was narrowed down to what she could make him feel, and he'd do practically anything for more.

She smiled, not caring that the Master's madness burned in her eyes.

She'd won. Finally, she had what she wanted most.

She was well aware that she never did break him entirely, but that hadn't been her intention. What she wanted was to mould him. Even after a year of experiencing every kind of humiliation and torture she (and the Master) could think to visit upon him, the Doctor was still desperate to keep the Master – to keep her, in other words – with him for the rest of their lives. Though that turned out not to be very long at all in the Master's case, the TARDIS found she didn't care overly. She'd done exactly what she set out to achieve.

While the Doctor cried over the Master's empty husk, the TARDIS settled smugly back into her own body, knowing that in no time at all he'd be returning to her.

They'd be alone together again, and this time the Doctor had better appreciate that.

She'd know exactly how to deal with it if he didn't.

She never fully realised it, but that spark of madness she'd shared while she'd been one with the Master didn't die with him.

She didn't need a human or even Time Lord body to occupy anymore to remember what it felt like to make the Doctor take notice of her. All she had to do was slide into the Doctor's memories, for he was so accustomed to her assault after a whole year of constant onslaught that he didn't even notice her slipping past his defences anymore.

His dreams were almost always of her and their time together. And she enjoyed every horrifying moment as much as she did the more pleasant ones.

Even if he didn't consciously realise it was her he was ultimately thinking about, that didn't bother her the way it had with Rose, for this time there was no question that it had been her he'd loved despite everything she'd done to him and others. It gratified the TARDIS that the Doctor was never quite able to get that time he spent completely dependent on her every cruel whim out of his head. She didn't mind that the love he tried to deny feeling for the Master (and for her by extension) was mixed with fear and scorn. That was a sacrifice she would willingly make to have him finally unable to ever just forget about her.

She enjoyed the idea of him craving something that he knew would hurt him, much as she had done for years. Finally she had justice.

He was certainly paying attention to her now.

That was how it would continue, and she would make sure that it was how it would end.

~FIN~