Such an idea was preposterous, and though his housemates were too stupid to see it themselves, Tom was determined to show them the error of their ways. He had spent the last four years researching his family tree for evidence of wizarding blood. Every jeer from his dormmates spurred him on. Every contemptuous glance, every moment of social exclusion, every refusal to socialize with him as an equal for fear of being sullied by association, became fuel to his fire.