If Nahadoth were a cat, what kind of cat would he be? :-)
He wouldn't be a cat. :) Naha's never taken on an animal form; that's for godlings to do, and Sieh's as close to what Naha would be like as a cat -- spectral and huge, with fur so black in color that it hurts the mind -- as it gets. Naha's doing good to take on a vaguely human form, really; most of the time Naha just wants to amorphously cloud around.