"The Man in the Well," like Lord of the Flies, shows how brutally children can act when they aren't bound by consequences and the normal rules of society. Outside of the standard norms, children aren't yet old enough to have developed consciences that make them react with empathy in groups. This is shown in both the story and the novel.
The children who find the man down the well decide to keep him there indefinitely. When they don't help at first by alerting their parents to what's going on, they decide to instead bring him food and keep him alive in the well. This backfires on them when he finds out what their actual names are; there is now the possibility that they could get in trouble. They choose their own self-interest over helping another human being and decide to leave him in the well rather than risk their parents being upset with them.
The children stranded on the island in Lord of the Flies experience this on a much greater scale. They are completely outside the realm of normal...
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