It's fifty years before Kyoshi's death, and a young boy arrives at the southern air temple. All his worldly possessions are carried in his pockets, and soon even those will be given up as he becomes a proper initiate of the Air Nomads. Like many, he is looking about in wonder at his new home, at the bright yellows and oranges of the clothes, at the adepts who fly through the air above the courtyards with laughter, at the ancient but well maintained stones that make up the buildings. 

His name is Rinzen.

It won't sink in for three days that he won't ever be going home again.

That's when the Abbot takes him aside, listens to the child Rinzen sob of all the things he misses from home, and holds him through the tears. When it's done and he's feeling as empty as a rice bowl after a lean year, the Abbot tells him of an important and ancient monastic tradition; that of pieing the temple Abbot in the face. 

A year later, Rinzen's days are long and joyful, and two years later he's one of those who pass along the pie tradition to the couple of stray newcomers to the temple. He hardly thinks of home.