Btw, I would like to see some twist like sudden appearance of new character, closely related to main characters, like Adrianna's mother or her former husband's sister, to move in to their house (at least temporary) or settle in neighborhood and put additional tension into the whole situation. I think it would be hilarious.
I think you just spoke my mind. I had this thought come into my mind not too long ago where a new, but "familiar" character (someone that Adrianna already knows from her past) joins in the story to potentially add more excitement into the plot. (Not that it's any bad right now by any means)
And who better would it be than Adrianna's mom herself who later would end up becoming next to MC too, just like Adrianna, but closer to Adrianna than rest of the harem, if that makes sense. Addition of grandma into the scenes would not only add new levels to the corruption in the game but also unlock deeper levels of depravity within Adrianna just as she has someone to look up to as a role model, and would do everything to become just how corrupted the grandma may have been in the past. She would gain more confidence looking at Grandma indulging in such acts and she would say to herself that if her mom can do it then she can too. Naturally, Adrianna would have sufficient training both from MC and Grandma. But it's only that the Grandma would train Adrianna in her own way in absence of MC, not as in femdom, but maybe giving Adrianna tips on how to "win" MC over more and more with her sluttier acts day by day.
Although, this is just an idea. So if there comes a new significant character ahead, it can be decided by a poll if people would hope to see such a character added into the game or not.
However, if the answer would be a no, or if Kalyha doesn't feel like it due to some reason, there's still an alternative way which could make it more interesting with Adrianna receiving inspiration/training by someone other than the MC anyway. And that in my opinion is, Scarlett, since she would become the perfect wingman to Adrianna (apart from her sister Jenna) in the later stages of corruption. And this could also happen after they've all moved into MC's house to cohabitate together.
It's just like that scene where Adrianna got super jealous of Scarlett when she was taking the lead with MC and MC "purposely" chose to enjoy the attention of Scarlett more than Adrianna herself. I think this could play on how to continue to corrupt and degrade Adrianna in the most depraved way possible in the future too.
For example, the mere premise of Adrianna being envious of girls in MC's harem, could lead the story to totally new heated scenes. Of course, the main source of envy for Adrianna would be Scarlett since she not only abides everything that MC says, but also goes a step ahead to please MC giving MC a pleasurable surprise element, which Adrianna clearly lacks (as she only does what she's told by the MC).
So Scarlett would not only teach her on how to become No. 1 Girl for MC in his harem, but also take her to a bimbofied route that would force Adrianna to become more and more whorish and shameless in both private and public. And by a bimbofied journey of Adrianna, I don't mean to give her bigger "assets", since her body is already perfect in the eyes of MC the way she is. But the mere fact of Adrianna being inspired by Scarlett into dressing more slutty, and get more and more inclined towards lewd make up and cosmetics (like doing long nails, lipstick, eye lashes, etc.). With the help of Scarlett in a twisted way, Adrianna would embark on this journey of becoming the best eye candy for MC, as conditioned by MC and Scarlett, while in the hopes of "impressing" the MC the most with her "efforts" in that direction, resulting into her falling into the rabbit hole of depravity inch by inch.
I also thought out this scene in later updates of the game where Adrianna's makeup kit, when she opens up her hangbag in public, would mostly contain glossy cosmetics and adult items, and in one of the scenes she could be seen applying her makeup just before and after it gets ruined by MC, haha
So to sum it up, Scarlett or this new character (if added) would be enough to push Adrianna beyond her limits, and encourage Adrianna into making herself the prettiest and sluttiest for MC. Not just merely out of jealousy and competition with other sluts in MC's harem but also because of this inbuilt insecurity of Adrianna, that the other girls don't "win" MC over while Adrianna is still there for MC. So she would always go extra mile, thanks to the encouragement by Scarlett or the new character, all in the hopes that MC would choose Adrianna over others more often when MC has her as an option. All this would happen while MC still gets to have fun with Adrianna and others as usual.
I personally feel this could really spice things up even more, and add extra layer of depravity to the ongoing plot.