The spouse who married into the madness. They provide the audience’s perspective: "Is this family normal?" They see the dysfunction with fresh eyes, but over time, they get sucked into the orbit. In The Godfather, Kay Adams is the ultimate Outsider, horrified by the Corleones, yet unable to leave.
Secrets are the currency of family drama. An affair. A second family. A crime. A disease. The longer the secret has been buried, the more explosive the reveal. Big Little Lies built an entire season around the secret of Perry’s abuse and the "accidental" death, showing how a group of mothers bonded by trauma creates a surrogate family that is as complex as a blood one.
The aging ruler refuses to cede control. The Shadow Successor is the child being "groomed" for power but is never actually given the keys. This creates a gothic tension where the child must wish for the parent’s death to achieve their own life.