Centuries ago, 3 eggs were found by 3 families, the winter was cold and they wouldnt be able to survive till spring so the familes took them in, when the eggs hatched, the three baby legendary birds stumbled out of their eggs, blind and hungry.
One of the women from the family that had hatched little Moltres decided to use her motar and pestle to crush up some berries, teaching the other families how to do so to feed the small birds.
They raised them for 10 generations, each family being carefull to raise the birds and teach them to survive in the cold Crown tundra. My family had hatched articuno, my ancestor was a wise man, having traveled with the birds when they could hunt to show them what berries were safe and which were not.
Once the 10 generations passed, before the new children were born, the three birds took flight to look for food and nesting areas. They soon returned but due to flying for so long, perched at the wrong houses.
That night, Articuno was perched on the Vailon rooftop when it heard a baby crying, assuming it was one of his own, he entered the house and perched next to the crib, laying his head next to the baby to calm them.
Ever since, they have watched over the families, taking flight every 10 generations to bring back necessary materials for the spring and to meet the new babies of their new families.
Its said that depending on what bird chooses the family is what trait the new child would have.
Zapdos brought lively and energetic children
Moltres brought passionate and sharp tounged children
And Articuno brought calm and smart children.