Fiona Peyton

Fiona is the younger daughter of Jackie and Kevin Peyton, a kid growing up half-aware that something in her house doesn't add up. She wants ordinary things — attention, stability, her mother present — in a family that keeps almost giving them to her. Mostly she watches the adults and waits.

Mackenzie Aladjem plays Fiona with the unshowy alertness of a child who's learned to read a room before speaking in it, which makes her a quiet barometer for the show's central lie. She doesn't need big scenes; her watchfulness alone measures exactly how much Jackie's double life is costing the people who trust her most.