Mario's birth and body — "Avril remembers Mario still wanting Hal…"
Avril remembers Mario still wanting Hal to help him with bathing and dressing at thirteen—an age when most un-challenged kids are ashamed of the very space their sound pink bodies take up—and wanting the help for Hal’s sake, not his own.
Context
Dependence inverted into gift: Mario keeps needing help he could do without because being helped is good for the helper. The em-dashed aside quietly flips the marked category — it's the "un-challenged" kids, ashamed of their sound pink bodies, who have the body-shame problem.