Final Answer:
Trevor's mother found out about what he had done in the house when his grandmother was there through a letter he wrote confessing his actions.
Step-by-step explanation:
The revelation of Trevor's actions came to light through a written confession. Trevor chose to communicate the details of his actions in a letter, possibly recognizing the gravity of the situation and feeling compelled to confess. This form of communication served as the vehicle for Trevor's admission and became the means by which his mother discovered the events that transpired in the house during his grandmother's presence.
The choice of a letter as the mode of disclosure may indicate a sense of remorse or acknowledgment of responsibility on Trevor's part. It provides a tangible record of his confession, allowing his mother to confront the information and assess the situation. The act of writing a letter can be a powerful way for individuals to express their feelings and convey complex emotions, making it a significant medium for Trevor to communicate the truth about his actions in the house.
The use of written communication in this context underscores the complexity of the situation, the emotional impact on Trevor, and the need for a thoughtful and considered approach to addressing the consequences of his actions. The letter becomes a pivotal moment in the narrative, shaping the dynamics of Trevor's relationship with his mother and influencing the subsequent events in the story.