I like the stories where the son is a wimp (nerd,gets bullied,virgin,small dick,etc) and has the hots for his mom and tries to peek in on her and goes through her clothes and masturbates to her. I like when the mom is consensually having sex im not into her being raped or forced against her will. The most against her will type thing im ok with would be agreeing to sex as a bargain (like to stop a bully from picking on the son) but she quickly enjoys it and is a willing participant. As for the partner obviously the sons bully is one option but I also like the sons friends or even his teacher or boss. The son would eventually witness his mother with the male and be aroused and jealous but continue to watch and masturbate. I like stories where the son gets involved instead of just watching or not even being aware of whats going on. Something I dont see much of but I really like is for the mother to catch the son and confront him but still be motherly and loving (lots of stories have the mother become very abusive and sometimes even disown the son and make him move out and im not really big on that). The mother would take a mother/cuckold relationship with the son where everyday life she is a sweet mother to him but privately she treats him like a cuckold lover where she has him help her get ready for her lover or lovers and has him watch then help clean her up. She could even give him rewards like getting to touch her or getting a handjob.