Inhumi as mirror-images of vampires
The nature of the inhumi may be one of Wolfe's trademark reversals. Dracula-type vampires are ex-humans, and by preying on living humans, make them vampires. Inhumi are aspiring humans, and by preying on living humans, try to become human themselves.
Having inhumi reflect vampires may be a little joke, since mirrors don't.
-- Dan Rabin
*This is WHORL, for discussion of Gene Wolfe's Book of the Long Sun.