So, potential spoilers ahead. Read at your own peril.
I just replayed the JKK quest line on a new character, and I forgot how disappointed I was with the end of Vivian's story. At no point can you talk to her father, the engineer, and bring up that you met his daughter. Once she is gone, she is just gone. It almost seems like there wasn't enough time and so the story just got cut short, which is understandable with so much other stuff going on in the game.
I have a simple solution, if a little morbid. Why can't we find Vivian's body somewhere after she disappears? Like down in the core city sewers, or at the bottom of the elevator shaft that we fell into for that quest? I think it would be a really simple fix that would add a lot of severity to the JKK organization, and some closure for those of us that felt attached to Vivian.