Do you know who you really are?
Ionan thought he did. King of the West, that's who he is. Though, having been sent to Camelot to grow up under the care and protection of his uncle, Uther Pendragon, being a king doesn't count for much. Especially when your cousin Arthur is very much bigger and stronger than you are. But still, he is a King. Mostly. It is undeniably more exciting to be able to transform yourself into a wolfhound or eagle when you want to. Provided your uncle doesn't catch you. So, that is who he is: Ionan, King of the West.
Until he reaches his majority, manages to reclaim his throne from his sister and is presented with the Staff of Bran ap Idris. Now he is more than a mere changeling who can become a wolf should he wish; now he can become a winged horse or even a dragon.
Though that, as it turns out, is only part of what he has inherited and so he still does not know who he really is.