Avatar Roku ( voiced by James Garrett and by Andrew Caldwell ( in the younger days ) ) is Aang 's immediate past life serving as his spiritual advisor .
Aang 's immediate past life is a Fire - bender Avatar .
Avatar Roku ( voiced by James Garrett and by Andrew Caldwell ( in the younger days ) ) is Aang 's immediate past life , a Fire - bender Avatar , serving as his spiritual advisor .