Marlon Bain’s Father
He used to do things “with” Marlon that involves Marlon standing around while his father does everything and doesn’t teach him anything. When Marlon or someone else mentions him not being a good father, it sends him into a depression (thus making him not a good father), which makes it so Marlon can never bring up anything bad or abusive he ever does.
Marlon Bain’s Mother
She is decapitated by a plummeting rotor blade (See Lateral Alice Moore) before she has much effect on Marlon’s older brother (See Below), himself, or his younger sister (See Below).
Marlon Bain’s older brother, and a member of the Inner Infant group at the Quabbin Recovery Systems, a place that Hal Incandenza accidentally stumbles upon while searching for a substance abuse group.
Marlon Bain’s Younger Sister
She is the younger sister of Marlon and Kevin Bain (See Above).