Final answer:
The 'end of chapter' lines feature a pessimistic and contemplative tone, reflecting characters' realization of the complexity of their situations and their lessons learned.
Step-by-step explanation:
The "end of chapter" lines quoted from different texts share a common thematic element of pessimism and a sense of desperation or disillusionment with the idea of a clear resolution to the problems presented.
The characters reflect on their situations with a newfound understanding that reality is more complex than they initially thought and that their initial hopes or assumptions were mistaken. This reflection often reveals a lesson learned or an acceptance of reality that indicates character development and sets a tone of contemplative unease about the future.