Only porn game I have ever played or been interested in so thanks for that! Just wanted to suggest some ideas for consideration and am not asking for any spoilers.
Maybe Luna and/or Serena gets captured at a rival syndicate brothel and is forced to temporarily "work" there?
Or she is captured and temporarily forced to be a stripper at a rival's club? This could introduce ntr opportunities such as a "performance" for a crowd/audience or a gangbang.
Or maybe she is captured during a mission and is "tortured/interrogated" for information? Could involve a fetish like "nipple penetration". Or a drug causes her to nipples to be very sensitive and lactate and thus is milked. And she could be fisted.
Aiden and/or Vargas could be forced to witness these performances (either in person or through a video/live broadcast) and then these scenarios are resolved by an eventual rescue. Maybe one of her outfits during these scenarios are nipple/x pasties.