From A Wiki of Ice and Fire
|Book||A Storm of Swords (mentioned)|
Aethan is a ranger of the Night's Watch of Castle Black.
A Storm of Swords
Aethan is part of the great ranging beyond the Wall led by Lord Commander Jeor Mormont, where he is under the command of Thoren Smallwood. Aethan draws watch the night conspirators intend to kill Jeor.