Every story needs a villain, that's true, but not that Lee dude, man his model is annoying, also the NTR part since I don't like it.
Just another fantasy storyline ahead:
The real villain of the Game should have been William and maybe his cronies, but mainly William's and Melinda's business rivals/ enemies. Hear me out.
Dev missed on the spot so far where he could slowly add Daniel into the Family's business, William's forceful actions. Him growing into it, thereby the boy slowly becoming a man kind of scenario. Which Melinda never wanted for him but his actions impressing her more and more. (derived from the frequent Respect references by Melinda's cronies, secret activities after church, and also William teaching Daniel to handle a gun)
Involvement of their business rivals, a little bit of action here and there, more number of characters, causing bloodshed, burying of more bodies. Hell make it all "Animal Kingdom" if you want to, just keep Melinda a bag of secrets that she is and not fully dirty, because she is everything about the game so far. (An external threat, someone other than William, derived from the scenes like someone is keeping an eye on Melinda references. Also the hotel scene when Daniel and Melinda visit and she's all prepared for an assault. Showcases the presence of someone big other than William)
Daniel getting full fledged into the Business, Jobs, Events etc, to Melinda's dismay, as she never wanted it for him, causing a small separation, which increases their passion more and more for each other. Only for them getting back together, in a violent passionate way, perhaps in the barn, so that they don't need to control themselves. End result being Melinda becoming pregnant. (Could or should be an on-off choice for people preferences.)
William finally figuring out 2+2=4, due to pregnancy angle or maybe catches them in action, leading to them both going for a drive together (maybe a ruse calling it a job), where William confronts him in a hot headed manner. But Daniel shares it with Melinda before leaving, who figures it out and tells him/preferably texts him to "Do what's necessary". Which acknowledges the fact that she is the biggest shot caller in the Family, as we have known her to be so far. MC coming back and saying, "It's done."
Mixture of fantasy and wishful thinking I guess.