Mario's birth & defects: the involuntarily constant smile

In a novel where nearly every smile is a rictus, a warning, or the Disease's have-a-nice-day mask on a lethal cartridge, Mario's is the one exception, and the adverb carries it: "involuntarily." His smile is not performed, not defensive, not a mask worn over anything — it is constant and beyond his control, sincerity rendered as pure physiology. Where the ironic smile is a face put on to keep the world out, Mario's is a face he cannot take off, and that helplessness is exactly what makes it trustworthy. The book's central image of the fraudulent grin has, in Mario, its single un-ironic instance: a smile with no gap between the expression and the thing expressed.