Walton the moral intermediary
Walton is a listener and his eagerness to discover is tempered by sensitivity and awareness of his responsibilites to his crew.
In looking at Victor, Walton's impressions and attitudes and beliefs become a benchmark for comparison. He has complete moments
of despondency, "My courage and my resolution is firm; but my hopes fluctuate, and my spirits are often depressed."
Contrasting Victor who is deliberate in his use of emotion. he shuts himself off from human contact, he is blindly obsessive in his quest and Walton is mistakeningly sees his drive and admires him.
Walton remains a social being, evident in his ability to praise the virtues of others and supress his own ambitions and turn south.
His selflessness means that he can survive his time in exile in the frozen wasteland and return home, enlightened and self-aware.

Walton's search lead him to Frankenstein's tale
Walton’s letters to his sister form a frame around the main narrative, Victor Frankenstein’s tragic story. Walton captains a North Pole–bound ship that gets trapped between sheets of ice. While waiting for the ice to thaw, he and his crew pick up Victor, weak and emaciated from his long chase after the monster. Victor recovers somewhat, tells Walton the story of his life, and then dies. Walton laments the death of a man with whom he felt a strong, meaningful friendship beginning to form.
Walton functions as the conduit through which the reader hears the story of Victor and his monster. However, he also plays a role that parallels Victor’s in many ways. Like Victor, Walton is an explorer, chasing after that “country of eternal light”—unpossessed knowledge. Victor’s influence on him is paradoxical: one moment he exhorts Walton’s almost-mutinous men to stay the path courageously, regardless of danger; the next, he serves as an abject example of the dangers of heedless scientific ambition. In his ultimate decision to terminate his treacherous pursuit, Walton serves as a foil (someone whose traits or actions contrast with, and thereby highlight, those of another character) to Victor, either not obsessive enough to risk almost-certain death or not courageous enough to allow his passion to drive him.