How does Frankenstein feel about his brothers death?

Frankenstein is profoundly devastated by the death of his brother William. He feels a deep sense of guilt and responsibility, as he believes that his own actions and the creation of the creature indirectly led to the tragedy. This loss intensifies his internal conflict and contributes to his growing obsession with seeking revenge on the creature he brought to life, highlighting the themes of loss and responsibility in Mary Shelley's novel.