During eighth period on the first day of school, Via tells Miranda that she doesn't need a ride home. It's a lie, but Via can't stomach sitting in the car with Miranda. Via takes the bus and the subway home by herself and lies to Mom that she's late because Miranda's mom bought them pizza. She gives Mom a little bit of information about her day and then asks about August's, which leads to a strange and dramatic fight when Mom acts as though she doesn't believe August had a good day.
In this situation, August makes a convenient cover for Via's pain and confusion—she can hide what's going on because she can easily shift the attention off of her and onto August. Mom's disbelief in August's assessment of his day suggests that she still thinks of him as being a child who wants to appease his parent, even though there's clear evidence to the contrary that August actually did have a decent day.
Via storms to August's room, moves Daisy over, and tries to ask him about school while he plays video games. He doesn't answer Via's question if kids were mean until Via pulls his controller away, and then he sarcastically asks why people would be mean to him. Via is shocked; she's never heard him be sarcastic before.
Via's shock at August's sarcasm suggests that as much as she'd like him to grow up and be more mature, it’s still strange for her to see that process underway.