Robert Walton's letters to his sister are the frame around which the novel is based. But Walton is more than just a convenient frame for the story; he is also a parallel to Victor in a way. Like Victor, Walton is an explorer, chasing after the unknown. Victor's influence on him causes him to at times cheer his new-found friend’s boldness and his journey, at other times to feel sorrow and fear at Victor’s abuse of both science and nature.
In this way, Mary Shelley uses the device of Walton’s letters to set a realistic tone for what is otherwise a completely fantastic story. Robert Walton is introduced as a pragmatic man, concerned with facts and the practical matters of his expedition. But he is also a Romantic adventurer, eager for the rewards of new experiences and sensitive to human emotions.
We also discover that Walton originally wanted to be a poet, but, having failed that endeavor, he embraced the scientific advancements of the age and became an Arctic explorer. Walton's letters begin and end the novel, framing Victor's and the creature's narratives in such a way that Walton embodies the most important qualities found in both Victor and his creature. Walton, in other words, balances the inquisitive yet presumptuously arrogant nature of Victor with the sympathetic, sensitive side of the creature.