Hmmm...Julia...
Right from the start and every time I see her, particularly her expressions and the some of the "camera's" focused attention on her, the more I get a "Stepford Wives" vibe about her. I'm wondering whether she might be the A.I. that the three were talking about being "bound to please" at the beginning?
She's absolutely besotted with the mc. She's ready to have sex with him any time he wants it (as discussed in the prologue), yet she has no problem with sharing him in an open relationship...ergo no "jealousy" reflex, something else talked about in the prologue.
She has a strange problem with being touched by anyone other than the mc, something emphasised several times including some very specific "camera" shots.
She seems very clearly to be "bound to please" the mc...her creator (or at least owner or master) perhaps, if not Carter, who seemed to be the primary driver of the whole, at that time at least, seemingly totally puerile concept of A.I., its grand purpose in life and its benefits to "mankind" in the prologue.
It may sound as though I don't think much of this story, but I can see much potential here for a fascinating exploration or perhaps, as this is an AVN, exploitation, not of the A.I. element, but of the social impact of the free availability of open relationship/harem where the usual barrier of human, especially human female, jealousy reflex has been, very cleverly here, removed.
Anyway, I'm not up to date with the story yet, so I apologize if there's already stuff which blows my theory out of the water, but this is my take on things based on what I've seen so far.
OH! and Stella...WOWOW!!! Simply the best...better than all the rest..!!