Final answer:
Peeta is surprised when he learns Thresh spared Katniss's life due to her connection with Rue and he struggles to understand this act of compassion within the brutal context of the Hunger Games.
Step-by-step explanation:
In the Hunger Games book, when Katniss tells Peeta that Thresh saved her life, Peeta is surprised and initially doesn't understand Thresh's motives. Peeta's reaction stems from his understanding of the games being every tribute for themselves. However, Thresh spared Katniss because of her alliance with Rue, Thresh's district partner, and the kindness she showed towards Rue. This act of compassion is something Peeta struggles to understand in the context of the deadly competition they are all participating in. Peeta's confusion might also be influenced by his strategy of forming alliances based on strategic value, while Thresh's decision came from a place of honor and respect for Rue's memory. This moment illustrates the complexity of human emotions and morality, even in the most dire circumstances, and underscores the theme of unexpected alliances and debts that cannot be repaid with traditional means within the Hunger Games narrative.