The TARDIS was one of the most incredible feats of technology - or perhaps evolution - to ever have existed. And this particular TARDIS was extraordinary, even by that standard. Past and future had little meaning for her. To be honest, she quite confused them sometimes, but really, how did people live in those tiny, little, linear flesh brains? Even her own Thief could be quite dense at times.
He was quite fond of telling people that he could see all that was, and all that ever could be, and he claimed to understand that there were things that must not ever come to pass, and things that were fixed, and must not ever change, but that never seemed to stop him from trying. And so it was left to her to remind him - sometimes rather forcefully - when he was about to cross a line. After all, she was the one whose data banks contained files of days and events that he had yet to live. She could see outcomes that even a Time Lord's brain could not envision.
When he'd brought the little Earth girl on board, the one with the yellow hair and brown - no, gold - all right, brown, but they were meant to be golden - eyes, the TARDIS felt a shimmer of recognition, as if a circuit was completed. At that particular time, all her Thief could see was a warm hand to hold, and a smile and laughter to ease his hearts, and she was grateful for that, because he thought himself so alone, so locked up in his pain. He didn't remember the girl, didn't remember how she'd saved him from making the most terrible mistake of his lives.
The TARDIS tried her best to keep him out of trouble, she really did, but sometimes she was limited by the fact that her Thief was able to actually walk outside and leave her behind. He'd really cheated dreadfully that day on Gallifrey…that terrible, terrible last day of the war. He'd walked for miles and miles, so that she would not be witness to the awful thing he intended to do, all unaware that she'd taken the precaution of embedding a tiny sliver of their golden girl inside his consciousness to keep him out of mischief. Did he really think that the Moment had chosen that image at random out of the clutter of his mind? How had he not noticed all the things that she knew about him? Even another sentient machine couldn't have picked that up without help. Silly idiot.
Much as the TARDIS loved her Thief, there were times when she was profoundly grateful for the presence of the girl - no, wolf - no, she was definitely a girl, the night she'd come upon the Doctor sitting on the floor of an empty cargo hold. He'd been in there for hours, and had collapsed in a boneless heap in the center of the room. The walls and floor were covered in groups of black-inked hash marks…2.47 billion, she knew. The number of children on the planet Gallifrey on the last day of the war. The children he believed he'd killed. He didn't - couldn't - remember yet, that they might not be dead. It would be centuries by his count, before he would be given that hope. So the TARDIS did the best she could, sending him their Earth girl, to offer him human comfort.
The TARDIS mourned their little Earth girl, the day she'd been lost to the void, and not just for the pain it caused her Thief. She and the girl were linked, which is why the TARDIS did something she'd never done before, and when the girl - no, she was more wolf, at that point - fought her way back across the void, she'd given a bit of herself, to grow into another TARDIS when she returned to that other universe.
The Thief had brought home many strays over the centuries. Some were human, some alien, and there were one or two that she'd rather heartily wanted to install airlocks for the express purpose of ejecting them, but this girl - no, wolf, she was definitely a wolf when she'd chosen to look into the Time Vortex - she was special. Very special. She was born of Earth, but she was most definitely a creature of time and space, and she was a part of the TARDIS and her Thief, now and forever.