How does Ishiguro use the character of Tommy to explore ideas about being an outsider?

Kathy's account of Tommy's youthful trials foreshadows one of the novel's major themes. Ishiguro does not suggest that people are immoral; rather, he portrays a world in which individuals always assume that someone else will take a stand for morality––and then no one does. It may seem crass to compare Tommy's bullying to mass slaughter, but this is part of the point––to Kathy and her peers, forced organ donations have become so commonplace that they are no more upsetting than a disturbance in the schoolyard.

Then there were rumours almost every day of pranks that had been played on him. ... I thought sooner or later someone would start saying it had gone too far, but it just kept on, and no one said anything.” pg 15