Paul

Paul was a student who attended Katie's school, but later got expelled for causing various troubles at school. He is a wizard.

At Katie's school
Paul stole Katie's spell book, as a series of bad actions he did after he became tired of constantly obeying the school rules. (The Wizard Who Stole Katie's Spells)

Paul cast a spell so that the actors would say the wrong lines during a school production of Romeo and Juliet. The actor playing Romeo said “I’m here you silly bat. Have you gone blind or what?” in response to the actor playing Juliet asking “O Romeo, Romeo, wherefore art thou Romeo?”. In response, Juliet says:

“Tis but thy name that is my enemy: What’s in a name? That which we call a sock By any other word would pong like your feet.” (The Witch Who Lost Her Spells)

As a result of the many bad actions Paul did at Katie's school, he was expelled. (The Wizard Who Stole Katie's Spells)