Quilla would defeat the Indians
Once Trisha hears that her father said that “If Quilla had been at Little Big Horn [a battle between the Indians and Americans, which the first ones won], the Indians would have lost.” The girl didn’t like these words, but actually she agreed with them. Here Larry meant that the woman was so stubborn and purposeful that nothing could stop her from doing what she had decided to do.
Inattention of mother and brother
The author ironically describes the moment when Trisha, having just got lost, was calling for a help, and she “would have been stunned to learn that her mother and brother were still locked in their argument and did not know, even yet, that Trisha was missing.” Here the author shows all the “essence” of the relationships between Trisha and her relatives. They didn’t pay attention to her when she was with them, and but they didn’t even notice that their own daughter and sister disappeared for a long time. They were always so obsessed with their miserable showdown that anything else was not important for them. And it played a cruel joke with them and with Trisha as well.
Coolness while getting lost in the forest
Once, while wandering in the forest Trisha “resettled her Sox cap (backward this time, because backward was cool).” This Trisha’s thought sounds ironically in the context, because it’s obvious that there are much more important things to think about in her state. But the author intentionally uses this irony, meaning that the little girl just wants to do something childish to feel herself in her common state and mood.