How about they ask me to use evidence and details from the text that support this trait

Depending on which trait you say they have you need to spots in the story were that trait is showing. Like if you chose the trait of being really brave you would go find an example of doing something that would scare most people like saving someone in a burning building or rescuing someone from really high up. A good example of some people with brave traits are firefighters, police officers, the navy, air force, the army, etc.