: Some time far in the past, a then-beautiful Shiver was
: sent into a comatose half-death like Myrdred's; over
: the years, her body aged and withered as she slept.
: Balor revived her and cast a glamour spell so that
: she'd appear beautiful to herself and (intermittently)
: to others, and could therefore preserve enough mental
: equilibrium to use her magical skills to the max.
: However, either the sleep spell couldn't be cancelled
: permanently, or the glamour spell couldn't be
: maintained permanently; either way, Shiver was forced
: to sleep periodically. To make her of some use during
: these periods, Balor allowed her dreamself to go forth
: as a Mahir and work for him, although its thought
: processes were curious and difficult even for him to
: understand.
This theory is a wonderful combination of all out ideas. However doesnt it seem more probable that Ravanna just came out at night while Shiver was sleeping? (like the beta-shades). After both Ravana's 2nd name and her nocturnal nature seem to point to this. In addition, she was adept at magically manifesting her dreams on the physical plane (Whisper/Nightmare Dream) so isnt it possible that at night, while unconcious, her dream self (Ravanna) could physically manifest herself? Perhaps she was insulted by the Deceiver's comment as not being able to surpress one's dream-self is a sighn of weakness to be ashamed of (shame which would be amplified by Shiver's vanity).
-Milky