Women in Mahabharata - Parishrami
She starts out as a maid of Ambika, who either comes from Kashi as part of the dowries, or is a local girl who is sold into the royal household after the sisters' marriage. Her name, Parishrami, is most probably something that she has earned over years of hard work. Her real name lies forgotten.
When Ambika is asked to face Vyasa for a second time for another niyoga process, she refuses and decks up Parishrami in her clothes and jewellery in an effort to trick Vyasa, and escape the ordeal.
Parishrami however is not as afraid as the princesses. She has probably seen much worse than just an un-bathed rishi. She therefore greets Vyasa with respect, offering him food and water, and the two of them spend most of the night simply talking.
It is abundantly clear to Vyasa, that this woman is not Ambika, but he does not raise a fuss. Vyasa most probably, in the early years of his life, has lived either with Satyavati, or with a family of an equal economic standing, before he was old enough to live with his father full-time. This allows him too, to be more free with this lady, who drinks in every word he speaks, now fascinated with his knowledge and demeanour [who knows, maybe the poet sang for her a few early chapters of the Mahabharata itself?].
To a young Vyasa, his first experiences of intimacy has been arguably quite jarring [due to no fault of the princesses', but still I would consider Vyasa equally as much of a victim in this particular scenario]. Now, from Parishrami, he learns what a healthy [honestly] 'date' should look like.
Once morning comes, the first thing that Vyasa tells Satyavati is that this woman must be set free and then given a mansion and a pension, equal in standing to the princesses, and respect worthy of a daughter-in-law of the queen-mother Satyavati herself [it is in this mansion itself that Vidura continues living, and later moves Kunti in as well, and it also is the same place where Krishna stays the night when he comes to bargain for peace].
Vyasa declares her son Vidura, to be both legally and biologically his son, and not Vichitraveerya's.
Parishrami most probably later moves in with Vyasa, along with Satyavati and the Kashi's princesses when Vyasa comes to fetch them after Pandu's death [or maybe even before that, to take care of his ashram or something, but there's no textual indication of her future either way].