If you want to know a person's character, you should observe how he treats people below him, not just how he gets along with people in the same position. I think this sentence is the most valuable experience I have learned from watching Harry Potter. It not only tells me how to understand a person, but also tells me how to behave, because when a person is the same as you or above you, the normal person's reaction will naturally be modest, so when he is in an advantageous position, his reaction can show his moral cultivation.