First of all, getting this out of the way...Yay! Rise of the Guardians was an awesome movie, even if the concept is ridiculous.

Second of all, yay a TF! In order to understand this TF, some context needs to be brought up. Rise of the Guardians is set in a place where the Guardians of Children(ex. Santa Claus) protect them from darkness with their wonders. Their power is fueled by faith--without children believing in them, they not only lose their power, but they become invisible and intangible to them. The movie also implies that they all used to be somebody before they were chosen to become a guardian.

Having said all that, here's my idea of who the Easter Bunny could have been: a nameless celtic pagan partaking in the celebration of Ēostre with a fellow clansman who was pregnant with their future chieftain. In life, he served as her warden. Unfortunately, her father came from an opposing clan and would not approve of this half-breed and so, in a drunken rage, waited at a grove in secret to murder the child in his daughter's womb. Unable to see the unborn heir be destroyed, the man jumped between them and took the blow instead, where he fell to the grove dead.

That moment, the Man in the Moon saw his sacrifice for the new beginning and, taking the broken corpse, remade it under the moonlight sky and the pagan soon awoke, reborn as the Easter Bunny. From then on, he would protect those who believed in him by continuing the practice of easter.

For those who saw the movie, I know they gave him a different backstory but this is more fun. At least for me, I think it's more fun when the subject is formerly human and not just animal to anthro. It's just me. :P

Anyway, enjoy now! ^.^