phone call with Orin about JOI's death (pp. 248–249)
So it’s never mentioned. Nobody talks about him. It’s taboo. […] Mario talks about him. About it.
Context
The father is contraband among the men who survived him. Asked who keeps Himself's memory alive, Hal says it's "a three-way tie" — meaning nobody — among himself, C.T., and the Moms; the subject is "taboo." The one exception is Mario, "sometimes," and only Mario, and only when Mario starts it. It's the same division the whole book keeps drawing: the damaged son is the only one who can speak the father plainly (cf. scene 010's midnight questions, scene 080's vigil), while the two undamaged sons can approach him only sideways, through jokes, forensics, and taboo. Grief here isn't private; it's forbidden, and it falls to the boy everyone else talks around.