22 upon arrival in the 'verse, Alex is of middle height and build with androgynous features, green eyes and curly red hair. Possible models included various boyish redheads Kris found attractive, such as Tilda Swinton, but was finally settled as Lauren Ambrose.
Alex dresses as a man, binding her breasts (unlike most Sues, they are of manageable size) and wearing trousers. She attempts to present herself as a man in movement and mannerisms; it is quite all right, however, if she is read as "gay." She knows she'll be able to remedy that misconception if necessary.
Alex likes girls and whiskey, not necessarily in that order. Sometimes the whiskey comes first, then the girls. She doesn't care, as long as they're both in supply. That's not to say she spends all of her time whoring around; she just takes fun when she finds it. She considers herself an eternal bachelor, but may indeed be fooling herself. She laughs easily, forgives quickly and is prone to stepping on more reserved toes.
History on the 'Verse
Arrival and the Tragic Love of Selena and Alex
After running away from home under unexplained circumstances involving an arranged marriage and a scullery maid, Alex arrived in Paris under the pretense, assiduously maintained, of being a man. She was careful in her pronouns and indeed her Suethor took pains to create an ambiguously gendered character. As Alex became familiar and her author less diligent, this began to slip, and certain people found out about "Alex." Nevertheless, she kept her trousers and her "trouser roles," singing countertenor or alto roles.
And then she met Selena, a lesbian ghost with whom Alex fell madly in love. It was not to be, however, and future events surrounding Selena's difficulty with corporeality and memory loss would eventually serve to separate them. Or so Alex thought.
The Era of Rochester
While strolled through the foyer one day, Alex met Lord Rochester and immediately recognized a kindred spirit. She ended up moving in with him when he took up residence in the townhouse of Nadir Khan. Despite her orientation, her compatibility with Rochester extended to the bedroom (and the kitchen, the living room, etc). However, their relationship was purely of the "friends with benefits" sort, and no expectations were ever extended on either side.
Over time, the two have become confidants and companions, as they share a similar philosophy about love. It is possible that this friendship represents the beginning of the Brandi/Kris intrigue.