It's just a means to an end, she tells herself, and her body is just a body. She's learned that over the years, years she's spent surviving in a universe that is NOT her own with a man who is NOT her father. She puts on her makeup like armor, chooses her clothes like weapons, because she will do anything to get back to her Doctor. There was hope in the beginning, just after she was stuck in this place, but Pete sidelined the Dimension Canon years ago. It was taking valuable time and resources away from other projects, he claimed, important projects: repairing the damage that the Torchwood in Rose's original universe had done to the environment in this alternate world, cleaning up the last of the Cyberfactories that mad Lumic had made—and duplicating alien technology, of course.
She had no allies in Torchwood; Jake barely knew her and Mickey, while sympathetic, only reminded her that the Doctor himself told Rose that it was impossible. Of course he had, but he liked impossible. It was what he did, what they did every day. And he'd just given up. She wasn't about to. She was Rose Tyler, Defender of the Earth, the valiant child, the lost girl—and the Bad Wolf. She ate impossible for breakfast.
It has taken her years to come this far. When she looks in the mirror she almost doesn't recognize her face, and she wonders briefly if the Doctor would realize who he is looking at if he could see her now. She tried every other way, she really did, but after Pete told her, flat out, that there was no way in hell he would allow her anywhere near the Dimension Canon technology she knew that traditional methods couldn't get her what she wants. She isn't a genius, not like Adam was, and she's not good with computers, not like Mickey, and she's definitely not an expert on temporal physics, like the Doctor, and she can't trust anyone.
It's far more sinister than she realized, this alternate universe. There's curfews and soldiers on the street corners with machine guns, and looming over everything the stylized 'T' that represents Torchwood. They've done good, she has to acknowledge, a lot of good—but absolute power corrupts absolutely, and she thinks that Pete might be finding this out. She tried telling her mum, tried showing her, but Jackie was happy and in love and she wouldn't hear a word that Rose said. When she dared to suggest that Pete was wrong, that what they were doing was wrong she got a slap for her trouble.
That was when she left, because she wanted her mum to be happy and if living in a fantasy world was what it took, well, she wouldn't spoil it. Not yet, and not like that. She was alone, cut off from her friends and her family—but she is brave, and clever (even if she isn't a genius) and desperate, and not too proud to use what she has. Rose Tyler is beautiful, after all. Years of running with the Doctor have kept her fit and toned her body to perfection, and she's cast off the last of her baby fat at last, lost the round cheeks she had when she first met him. She is fierce and mysterious and she's spent the last two years of her life in the presence of one of the most powerful beings in the multiverse—little, if anything can phase her.
She moves out of London and picks a new name. As ever, it is the Doctor who gives her the inspiration. He'd always loved Sherlock Holmes and would rhapsodize about Conan Doyle's brilliance and that of the instructor on which he based Holmes. He often paid special attention to the only woman of note, according to the famous detective—the only woman to beat him. It is slow, her transition from Rose Tyler, former Torchwood agent to Irene Adler, professional scolder, but it is lucrative and occasionally pleasant. This world with its rules and restrictions closes around her throat like a noose and in her position she finds a strange sort of freedom. It isn't proper, what she does, and that gives her power—because powerful men and women like her. They like her breasts and her lips and her thighs and the way she handles a riding crop. And she, well, she likes the leverage.
She doesn't realize at first that the books which the Doctor so loved are real here, that there is a brilliant man named Sherlock Holmes who is halfway towards discovering that he is on the side of the angels not because it's a challenge, but because he believes it is right. Here there is a Mycroft Holmes who runs the government under the auspices of Vitex Industry because he believes that controlling the population is the only way to minimize suffering. Here there is a James Moriarty who finds a reason to survive for a little longer, at least, in the quest to break a rival on the harsh flagstones of what he believes to be reality.
She doesn't realize that Sherlock is real—until she needs him. Until she has worked for years, followed leads and discovered what thousands of people with little bits of information like and exploited that. Until she is standing at the precipice with all the bits and pieces that will make the Canon work—until all she needs is a man who can put them together. Then, then she hears the name of Sherlock Holmes whispered in dark circles as a man who likes puzzles and challenges.
A smile curves her lips as she regards herself in the mirror. She has always been fond of a challenge.