Mario's birth and body — "it was in fact not Mario’s…"
it was in fact not Mario’s real eyelid—that had been sacrificed when the fist stuck to his face like a tongue to cold metal had been peeled away, at nativity—but an extremely advanced blepharoprosthesis of dermal fibropolymer studded with horsehair lashes that curved out into space well beyond the reach of his other lid’s lashes and together with the lazy lid-action itself gave even Mario’s most neutral expression the character of an oddly friendly pirate’s squint. Together with the involuntarily constant smile.
Context
The prosthetic eyelid, paid for at birth by the fist "stuck to his face like a tongue to cold metal," and the two facial constants it produces: the friendly pirate's squint and the involuntary smile. Carlisle reads the smile against the book's smile-system — constant smiles are elsewhere the Entertainment's danger-sign, and Mario is the one benign exception (recorded, not adopted).