What is Leslie and Owen's relationship like?

Owen is mean and surly toward Leslie; however, they love each other, and she covers for him and lets him be mean to her.
When A wakes up on Day 5995 as Leslie Wong, he's frustrated because it's better to be an only child. It's clear in the morning that Leslie and her brother, Owen, have some issues between them. He glares at her and then insists that she not judge him for smoking pot on the way to school.
At the end of the day, A can tell that Leslie's family thinks she'll still take up for Owen despite the issues between the siblings. They say that she always does it. She still pretends like she doesn't understand why the two boys fought.
Later, A is more assertive toward Owen than he thinks Leslie ever is. He's hoping that in the future, it will improve things in Leslie's life and Owen will be less mean to her; it's what he thinks Rhiannon would want him to do.