Why was the reader a little uneasy about the stranger in Tuck Everlasting?

In "Tuck Everlasting," the reader feels uneasy about the stranger, particularly due to his mysterious demeanor and unsettling presence. His knowledge about the Tuck family and their secret suggests that he has ulterior motives, raising suspicions about his intentions. Additionally, his unsettling behavior hints at a darker side, amplifying the tension and uncertainty surrounding his character. This sense of foreboding contributes to the overall theme of the novel, emphasizing the complexities of immortality and the consequences that come with it.