On (novel)

On is a science fiction novel by British author Adam Roberts, published in 2001. The novel's premise revolves around a world where all humans are physically attached to another person, a parasitic twin-like relationship that profoundly impacts society, psychology, and interpersonal relationships.

The narrative follows the protagonist, Duncan, and his "on," Melanie, as they navigate this unique social structure. The presence of the "on" is not merely a physical burden; it dictates aspects of identity, career options, and romantic possibilities. The relationship between Duncan and Melanie is often strained and complex, reflecting the wider social anxieties and implications of this enforced intimacy.

Roberts explores a range of themes through this central conceit, including identity, free will, the nature of individuality, and the societal impact of mandatory connection. The novel delves into the psychological effects of always being physically connected to another person, examining the potential for both profound understanding and suffocating co-dependence.

"On" received critical acclaim for its imaginative premise and thought-provoking exploration of human connection and its limitations. It is considered a significant work within the science fiction genre, often praised for its originality and its challenging questions about what it means to be an individual within a constantly networked society. The novel stands out for its focus on interpersonal relationships and the psychological consequences of its central science fictional element, rather than relying heavily on technological extrapolation or grand-scale world-building.