Marie uses “what matters?” as an expression. It’s kind of an interesting one. I’m not exactly sure how she came up with it, but it is something she figured out on her own. It means something like “what does it matter?” or “who cares?”. For example:
Dad: “Are you going to wear your brown shoes or your white shoes today?”
Marie: “What matters?”
Eventually things like this disappear and we forget they were ever said. What matters?