Aurelia

What we know

We don't know much about her background, but she does seem to be soft spoken, and desperate. She isn't directly mentioned in the writings, but she's one of the spawn that come to try and abduct Astarion in act 3. If you pass enough persuasion checks, she'll ask you for help--before Cazador compels her, and she implores Astarion to run before she hurts him against her will. 

Where we see her

As with all, we see her twice! During the kidnapping attempt of Astarion, and during the final ritual. After stopping the ritual, if you interact with her without Astarion, she'll throw her hands up and proclaim that none of them are threats, and that they can disappear into the underdark if you let them live. Indeed, she's the most anxious of the group here, truly seeming scared, and desperate for another chance at life. Notable is that as the tav, you can tell her that they're "all victims" and choose to set them free. She'll thank you, and they all go off. 

Theories

Not really many for her! She seems very naive, and uneasy. She definitely carries a lot of anxiety in the group and shows it during both her interactions.

It is my personal belief that she is the oldest of the spawn. There is evidence to confirm that several of the spawn have to be relatively "newer", and Astarion only says he was one of the first. Personally, I would believe Aurelia to be the eldest, and perhaps this is why she's as traumatized as she is.

Otherwise to my knowledge, no other major theories have been brought forth with significant evidence to back them..