Except he is not high rank Drow ... :-/
I have read somewhere that tatoo on her neck marks her not as member of important family, but as a property of important family ... meaning she was probably even slave.
Either way, it can be explained away. Long hair, short hair, whether slave or high rank.
But, again, assumptions made by many. The tattoo is never explained as a slave mark. That is just someone's fan theory. She is called Minthara Baenre, and if you question her corpse, she says she is "of House Baenre." The tattoo is also the Baenre House Crest. It is the symbol of a very high drow family.
Now, House Baenre was the first drow house of Menzoberranzan, and had been for centuries -- as long as anyone in the city could remember. It was the oldest (around 5,000 years old), strongest, and most prestigious house in the city. Just the fact that she says she is of that house, it is, therefore, implied that she was not some slave or underling, but she was an established member of the most prominent of drow houses. If you right click on her, she is even called Minthara Baenre.
I'm not sure where they got it from, as I don't remember this being in the game, but Forgotten Realms Wiki states, "Many members of her family, along with her friends and former lovers were all killed at the hands of others."
So, I have to wonder what happened to House Baenre? The last historical information any books and such from Forgotten Realms gives us is that House Baenre was still going strong in something like 1484 DR, 8 years prior to the game.
So, I have to wonder... could House Baenre have suffered from some sort of attack? What if Minthara's past is linked to Eliette's, the Spider Matriarch's? Wouldn't that kind of make sense?
What did one of Eliette's journals mention? There was an upheaval of a drow house where some unnamed individual slit the matron mother's throat. During the resulting conflict, Eliette escaped. Could it be that House Baenre's Matron Mother was assassinated, resulting in a huge drow civil war for her position which resulted in the deaths of Minthara's loved ones? Are we going to learn of this somewhere in the game?
Who knows? It's all speculation. Either way, I don't think she was a slave since she would not be called Minthara Baenre if she was. No, I think - Fan Theory, mind you - that Minthara was a member of this prominent house, some unnamed assassin killed the Matron Mother, drow from all houses, including within her own house, started to try to claim the Matron Mother position, Minthara's family and loved ones were butchered, and as a result, Minthara found the Absolute who gave her new purpose and the ability to avenge those she lost.
That seems the more likely story for her, at least to me, and it would then tie into all the drow stuff going on in the game. Major power vacuum created, and in steps the Absolute to take advantage of it.