Why is Meg so emotional?

Meg's emotions are all over the boards, she feels things more deeply than any other character in the story. She misses her father and would do anything to bring him home, she fears the unknown, and she loves her family without reservation. Meg's strength and ability to demonstrate her emotions are the reason she, and only she, can battle IT. Her emotions make her strongers than the others and are an integral part of her ability to get her family (and Calvin) home safely.