Suspicion and Paranoia

The narrative is driven by mutual distrust—the islanders suspect the stranger, the protagonist suspects nearly everyone (the doctor, O'Brien, the Scollays), and even allies like Bolton and Whiteclett question each other's motives, showing how war breeds pervasive uncertainty.

The protagonist's every thought is consumed by whether the stranger suspects him, leading to a state of heightened anxiety and self-doubt.

The protagonist is suspicious of everyone, and the Scollay family is wary of him. The atmosphere is charged with mutual distrust, reflecting the wartime paranoia about spies.

Both Thomas and Dr. Rendall are wary of each other, with Thomas noting the doctor's 'trace of suspicion' and his own 'mixed emotions' upon leaving.

The narrator's growing distrust of everyone, including the old man and the Rendalls.