Her name, (obviously). She liked the mystery and the anonymity that came with not having an official name. Indeed, it'd been so long since she'd heard her actual name that she'd forgotten what it was. But that didn't matter anymore. At the beginning of the every day, Mycroft would always say "Good morning..." and she would fill in the blank. She only wondered what she would do when she ran out of names.

What she meant to Mycroft Holmes was constantly in flux. Some days she was his secretary, others his assistant, once his bodyguard, sometimes his confidante, occasionally his caretaker - but always his friend, and always his equal.

Her personal life was just a downright chaotic disaster. Her family assumed she was unemployed, only because she got so tired of making up a new job every time she ran into one of them. Boyfriends, girlfriends, neighbors, nieces, nephews, uncles, cousins - everybody she came into contact with, really - wanted to know about her job. Most of them were assassins, or spies, or foreign agents trying to get secret information out of her.

She's a variable, Mycroft's a constant, but they get along well enough.