She hated him. He wasn't the man for the job. He was going to get them all killed.
He hated her. She wanted to be in charge and took unnecessary risks. They were completely, incompatible.
Prudence Brinker was an outcast, a big 0 on the popular scale. So when Harry Styles, the most popular guy in school, takes a liking to her, and is worse, taking singing lessons from her, what could go wrong?