Tommy has difficulties with discipline and social conformity. He acts out in school and his misbehavior gets him into trouble. The society portrayed in Ishiguro's novel imagines a subculture in which young people are raised in regimented ways to prepare them to be organ donors. They are expected to follow strict rules to safeguard their physical well-being, and are kept sheltered from the world at large. Tommy's tendency to disobey the rules at school show he has a strong-willed personality. He is also an artist and uses his drawings to help prove to Madam that he deserves a deferral because his artistic temperament (as well as his long-time love for Kathy) makes him special.
Tommy also manages to survive three donation procedures with no apparent ill effects, whereas it is said that many donors only survive two, or at least experience severe health problems after their first donation. His urge to survive and his violent outburst at being told there are no deferrals reinforce the idea that he is very aware of his unique individuality, and that the system is unfair in its relegation of him and Kathy to the pool of organ donors who are effectively raised for slaughter (perhaps a commentary on huge corporate agriculture practices). The fact that they are clones does not detract from Tommy's strng sense of his own individuality.