Friends could be a huge part of one's social and character development as one grow up. Children were often told by their parents to choose their friends wisely because they will influence their actions as they grow up.
But with Nora, Sadie, and Megan, they did not get to choose each other. They were born for each other. It was as if it was fated in the stars that they would be born friends. No words are needed. It just happens as if it was meant to be.
They were friends even when they weren't born yet.
As they grew up, they realized their differences, nevertheless, they still clicked together. They learned to adjust and adapt to each other's differences.
They had met other friends outside their circle as they started to go to school but with each other, it was different. They can only be themselves with each other.