You cast a shadow that is not of yourself. A shadow who is a woman. A woman whose role requires her never to be more than precisely what you need her to be. How strange that you two can leave less trace than most individuals on their own. You are yourself and also more than yourself. Her voice follows after yours. Her fingernails click softly over that Blackberry as constant as your heartbeat.
It pleases you to think of her as your shadow. Even in pitch darkness, a shadow and the one who casts it are never truly parted, after a fashion. The shadow simply overwhelms the caster.
You know that she is well above par in every capacity one would expect of a woman in her position and some added excellence beyond that (prodigious ability computer science would have been a prerequisite had you set out an official list, but a strong and elegant fencing form can only be considered a fortuitous bonus). If she were inclined, she could distinguish herself in half a dozen fields rather than remain out of sight in this line of work. And she is not only her work (just as you are not only yours, a fact for which you are sometimes glad and at other times find yourself bitter). She does not come from nowhere. She is not of herself alone.
But you do not care.
(This isn't technically true. Rather, you have schooled yourself in not showing that caring needlessly. You dole out such acts of kindness with a measured hand. You count this mildness of passion in such matters among your virtues. You know her family in all their vital statistics- health and birthdays and careers- and acknowledge these things when the proper opportunities arise. You discuss them only rarely; what you do for them even less often, but she knows. You know that she knows. This matters.)
Practicality must trump personal feeling. Between she and Britain, you know what you would have to choose. It becomes vital, therefore, never to be placed in a position to even have to give the most momentary thought to the possibility of facing that choice. For all that you know of one another, you remain beyond arm's length. There is something to be said for the charm of retaining such mystery. Even what you know, you may act like you do not. You dance around one another in this manner, locked in rhythm, with bodies that never touch and eyes that never meet.
It makes perfect sense, but that doesn't mean it makes you happy. But your duty is to sense, not happiness. She is a practical woman. You would trust her to do the same if your places in this hypothetical scenario were reversed.
You are always so definitively you. No one will ever see or speak to you once and then mistake you for anyone but Mycroft. To transform, you must always keep yourself at a distance. But your shadow is not just a reflection of you. She is more; she can transform, with the smallest of gestures and the appropriate look in her eye. If she is no one, she can be anyone.
With a one-woman arsenal, you are well attended. You can take or send her anywhere and be secure in your knowledge that she will morph to match the situation.
This is a story where she is often of the utmost importance, but can never become a full-fledged character. As fine a heroine as she might make, she is needed more as a minor player who steps up to fill many parts, appearing suddenly in a cab or warehouse or materializing out of the rain. Whoever knew such a lovely deus ex machina?
The hero of this story is your brother (though you would never deign to tell him- his ridiculous ego hardly requires such fuel, even assuming he did believe you). You never intended to take on such a role (yours is a higher position in the story than hero). You should've known things would turn out like this- he has the right kind of mind for it and with the proper prodding he can even occasionally summon the heart to match (and that mind is needed with far greater frequency than a heart after all). He rises up to act and you make a move- a call usually, or a properly encrypted email- and shuffle things into place.
Even the finest hero can use helpers to smooth his way. And you, the helper in question, have the only the finest helper of your own (multipurpose as a Swiss Army knife, but even in her blandest accomplishment of neutrality, always a person, never just a tool). You can trust her to be your eyes, your ears, your hands- she can be you wherever you cannot be.
To some tasks, she brings something you could not. She shuffles John Watson about masterfully. The reasons she befuddles him are not identical to the reasons you do.
You do not write this tale; you do not direct it. You are not the master of marionettes. You are the architect you always dreamt you might be. Such little lives are your design. Each beam, each arch, they fall together to support the whole so perfectly. Better than any sandcastle or tower of blocks for the ocean or your brother to knock down, though they are transient in their own way (each part remains as foundation for those to come). You are proud of your works.
She could have created as well, if she had chosen that path. She is aware of things and sees the ways they come together and move apart. The words she weaves onscreen and, sparingly, in person, could create worlds of fiction, fairly, in a novel, or treacherously, toward the completion of whatever con she chose. She can be whoever she wants to be.
She choses to be your shadow; the cipher this role requires of her.
You don't know everything about her. You don't know what she would have done had she walked the road that never brought her to you. Where there are true mysteries remaining between you, there is freedom to wonder.
You have given her this role, but you did not create her. All these things were present in her all along. You have guided her a little, is all. She has seen and knows so much that no one can deceive her now, not even herself. Where some might regret this loss, she seems to regard it with a degree of fondness, like a gift one would never think to ask for and may initially be skeptical of, but comes to enjoy nonetheless. Or perhaps you flatter yourself to think that anything you give could be meaningful or grand (you grasp as grand things- they have always delighted you- but, in the end, is anything that issues from you not to fuel the tasks of your position more grand than grandiloquent?).
Nevertheless, it is one of the only gifts you will ever give her (it is not the only one she deserves).