A bit of a disclaimer: what follows is an extremely resource-taxing suggestion. I would be perfectly fine with the outcome if it was rejected outright or if its consideration was postponed until after the optimization stagedue to technical limitations and the sheer amount of coding involved. However, in my humble opinion, it would be extremely cool to see this in the final version of the game, even if it was part of a post-release update.

Ability to create flaming characters, with the ability to fine-tune the flames individually for each allowed body part in terms of its intensity, color, temperature and sensitivity of all of the parameters above to arousal and stimulation levels. Possibly, with an extremely nerfed fire breath.

Adding additional dialogue for reaction to the fact the character is about to either fuck somebody as or be fucked by a living walking torch. Setting default interactions as temperature play adjacent if the used body part had been customized in this fashion and its temperature is sufficiently high or low. In a nutshell, integrating the system fairly smoothly by adjusting relevant behavioir patterns.

As I said, this is a really daunting challenge for the dev to code and implement this feature. Maybe it is even more of a challenge for whatever rig may run the game to not go up in flames immediately after a character enveloped in flames is shown. But a man can dream, right?

Because making a full-fledged demon or a somewhat functional dragon would be rad as hell. 

P. S. Recasting all of this for icy mist and cold breath would be amazing too.

Currently, drugs apply their effects when administered.

I'd like to suggest the ability to make drugs that are persistent and/or have effects based on other triggers. The most obvious example would be a drug that after taken, would apply some effect (ex. grow X%) each time a subject orgasms.

Players could even use this to setup chains with multiple drugs, or even complete/repeating cycles.

Currently, you're stuck choosing default patterns and decals for your characters.
While custom patterns/decals are probably going to be in the final game, I have a related idea.

In an editor similar to the decal adder, you could 'paint' a color onto your character, with various brush and erase tools. The result would be a custom layer, fine-tuned to your character settings.

Im not a diaper fetish person for the baby aspect, but for the cuteness and humiliation factor, I get it doesn't tickle everyone fancy but its just what my fetish is, but it could also just be a peice of atterire

The ability to attach a device to your subjects that lets you control their bodies while they're conscious, allowing you to make them say and do things involuntarily such as masturbate or have sex, but with visible intention to resist.

I think it's good idea.

If Electric masturbator(For Example CycloneX10 etc...) works as Character's orgasms Player can Experience sessions on Rack Laboratory more realistically.

The ability to change a subjets gender thru perhaps potions or vials, perhaps because you like to try it out on the subjet? or perhaps they came to get the gender changed? As well as bimbofying them to start to get abit less brain activity if you woulc continue to have your way with them for quite a while. Maybe if made into possible to turn off and on the feture.