: We are told that all shades were once avatars and as yet,
: in the Myth world we have yet to meet an evil avatar.
: As for Fallen Lords, we know at least some of them
: were once good, e.g. Damas/SB, Connacht/Balor, and
: Myrdred/The Deceiver. The histories of Ravanna/Shiver
: and Bahl'al/The Watcher are more clouded, since we
: don't know much about their pasts.
Myrdred was an Avatara, and he turned evil. All Shades we know of were once avatara, who turned evil and in doing so became Shades. You can't be an Avatara and evil at the same time - they'd kick you out if you were evil, and you'd just be a generic uber-powerfull villian. That, or you'd sell your soul and become a Shade.