Why did Grayson feel unburdened for the first time in 37 years?

At this point in the story, Maniac’s room has been furnished with various items Grayson has brought like , a space heater, refrigerator, blankets, and a toaster oven. Maniac fixes Grayson a celebratory desert: corn muffin and apple juice. Maniac persuades Grayson to stay the night. They read the "little engine that could" and Grayson feels a strange sense of contentment. As Grayson drifts off to sleep, he feels unburdened for the first time in 37 years, he feels love for the first time: he whispers, “Amen.”