Most often seen as an actual owl or immense eagle (or occasionally something significantly smaller), but will assume his human-as-bird appearance when interacting with mortals. Those interactions are rare, however, as he does not wish to be seen as an oracle or a shortcut for finding truth for oneself. More often his appearances are in support of art, whether offering encouragement or inspiration, or more material assistance.
Erestyrin is one of the few inquisitors known to take openly aggressive action. Often it is to protect wildlife he feels threatened by mortals in some way. Other actions seem to come without cause or provocation, not even to influence major events or threats. His reasons are known only to him. Where general consensus is that the inquisitors are neutral and largely uninvolved, no one is certain of Erestyrin’s motives or objectives, or even if he has them.