Jack's deceased wife who tragically killed herself and their two children six years ago based on false suspicions of an affair. Her memory and the sound of her laughter haunt Jack, contributing to his severe psychological trauma and final breakdown.
Alex intervenes when Jack's trauma-induced hallucinations of Susan escalate to violence.
Caswell's case indirectly addresses the psychological fallout stemming from Susan's death.
Borman's actions and Susan's death both serve as catalysts for paranoia and trauma.
Kat's site observations parallel the psychological themes triggered by Susan's death.
Explore the full interactive character relationship map of Nine Miles Down