The rivalry between Santa Claus and the Easter Bunny is a long and dramatic one.
In E. Aster Bunnymund and the Warrior Eggs at the Earth's Core!, North and Bunny made their first impressions under dire circumstances. North and Katherine searched for a way to the center of the Earth where Pitch was mining lead for his army. Bunny had the only means of transport, as well as one of the sacred artifacts of the Golden Age (in the form of an egg on his staff). However, Bunny was uninterested in helping in any sense, and responded to theft of the egg with lethal force. Katherine managed to trick him, making him think that Pitch Black and his fearlings hated eggs and chocolate (which Bunny had a strange obsession with), and Bunny agreed to help them fight Pitch. Bunny has since become a Guardian of Childhood and Protector of Santoff Claussen.
North and Bunny found one another obnoxious at first. North hated Bunny's obsession with eggs, snobby attitude and ambivalence to humanity, while Bunny thought North to be barbaric and dimwitted. The two were able to bond in battle, and eventually became best friends.
In Rise of the Guardians, North and Bunny hold a comradery that has lived throughout the ages. Possibly attributed to Bunny's stubborness and North's confidence, the two are in constant competition over which of their holidays is superior. Unlike Bunny's relationship with Jack, the two hold no particular grudge and act as comrads of war, pushing each other's buttons consistantly.
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