Promises. Rise of the guardians

When he was six years old, Noah was handed a golden egg necklace by the Easter Bunny that held a promise. A promise that Bunny was gonna visit Noah once a year every year near Easter, seeing as Noah was moving and wouldn't get to see him as much.

The Easter Bunny doesn't keep his promise.

After moving back, the seemingly normal boy meets someone new to believe in, and becomes, a guardian.