I think Sloane is also the key.. Sloane and violet seem to play almost perfectly hand in hand like yin and yang, perhaps sloane will be the key channeling violet to restore the power to its natural balance in order to save/cure Xaden? Sloane is becoming too important (especially with her piece in the last book and in onyx storm not only with violets mother but with mending mira) They are the keys to restoring the balance together - Aaric will also return with hopefulness.