In the Divorce AU, Lynn remains mostly clueless about Isabelle but she does quickly realize Alec is a ruthless person who has an. interesting relationship with the very concept of consent, something she personally enjoys but feels gross about whenever she thinks about his previous relationships, so she tries not to think too hard about it. If Cy were to end up dating Isabelle in that AU, he'd quickly clock who Alec is and what he did but not tell anything because he wouldn't want Alec to know Isabelle is around here and potentially putting her in any danger.