(I dunno how late this is to talk about since I dunno when the scene got added. Also gonna use Jill for ease) So this officially answers Jill's side of the question a lot of us(I think) would have had in the past, huh? the question of whether or not Jill would be down for incestuous romance.(we could have always answered that question for our own character, but not for her) Because I feel like it took almost no effort to get Jill into the idea of you servicing her, and she wasn't fully aware of the circumstances per se, she could only have really thought "my cousin wants in my pants, I guess that's fine by me if I'm getting pleasured"(so that means that at basically any point in the story she should be fine with you saying you'd give her oral? maybe?)
It also gives a few extra tidbits of personality to Jill, for one, she treated it actually kind of intimately(I'm saying this in comparison to most other scenes in game), rather than like coldly using a toy. And secondly, it shows that despite being bossy, Jill is not a dominant person imo, stuttering/failing at name calling you just cause of what you were doing, and not doing anything mean to you at all despite your vulnerability, so I feel like she'd definitely want to be in charge, but that her being in charge would kind of be up to the player.
I dunno how much characterization sticks depending on who is writing the scenes though?(I imagine/hope this is accurate characterization of her tho)
Also if you don't know what scene this is about, there's a scene on Uveto where you pick up a metal device(Sub-Tuner) directly north of your ship, it mind controls you, and then when you go back to the place it took you, you can pick exhibition, which can have you wander Uveto looking for someone to please, so it's random chance you'll get Jill.(Idk if there's any pre-reqs, but for me Jill didn't show up till I 'saved' her on Myrellion, could have been luck tho)