what about a buddhist-djinn type of desire? sorry for the many images!
and maybe more normal fighting human desires:
(sorry my first comment is 3 messages below, might make more sense to read from there~)
and random events like finding them in the kitchen could be stroking the boys to add some "flavor" to a meal theyre making, or eating something off them, or oiling up their bodies, adding a love potion to their food to get them aroused in the kitchen for a spicy event, etc, etc? lots of possibilities for random naughty events ;)
and possibly random events like a desire sleeping naked/in underwear on a couch in your mansion, and you can play with them in sleep or wake them up? Again an example image of one possibly just waking up to you ;)
Personally I think normal events like the desires sleeping, getting ready for a shower, finding something to eat, etc would be more suited as random events, and the more deep conversations could be relationship milestones?
I really like the full portraits and idea for changing their outfits as their affection increases, and would it also be possible for their facial expressions and pose to change depending on their HP as well (like what's currently implemented in the menu)? Like maybe when low they're blushing and have to lean on the side of the box or look semi-collapsed, and when defeated just collapsed at the bottom or looking really embarrassed or crying depending on their personality?