Whispers is the character's level of psychic connection to the Neverborn and how much their voices reverberate through the character's mind. The Labyrinth is filled with the voices of the Neverborn, things like the Labyrinth that are constantly being consumed by Oblivion yet never diminish. Abyssal characters may have Whispers from character creation without ever having been to the Labyrinth. They appear in the character's mind with no known cause like the visions in the mind of Jack Walters.
Avatar represents the character's connection to the Void. All Nephwracks have it as well as Spectres unless you'd rather have Spectres being ghosts that serve Oblivion whereas Nephwracks have been 'consecrated' by it. The dark hunger that exists within the Void exists in them.
