Mary Shelley's novel Frankenstein was written during the Romantic period (1789-1832). Written in 1818, the novel possesses characteristics true to both the Romantic and Gothic traditions. In regards to the Gothic tradition, the novel contains elements of the supernatural, decaying scenery, and mystery. In regards to the Romantic elements, nature is by far the most prominent characteristic.
The Romantics adored imagination over reality, individualism over society, and elevated the power of nature. Many times, authors personified nature (giving nature the power of mankind). As for the influence of Romanticism over the characters of Victor Frankenstein and Robert Walton, much can be readily seen.
Victor's life in science began with a lightening strike to a tree. The lightening strike utterly demolished a tree on the Frankenstein property. After bearing witness to the power of nature, Victor picked up the works of Cornelius Agrippa. From this point forward, nature's impact on Victor was sealed. For example, each time Victor became ill, nature cured him. It was the promise of spring and the renewal of life which would bring Victor hope of good to come. In the end, it was nature which ended up taking Victor's life--given he sought out his creature until half frozen to death (only dying once he is able to pass his story onto Walton).
Robert Walton, like Victor, is a highly ambitious man. His one desire, to find the seat of magnetism and establish new trading routes, leads him to the North Pole on a scientific expedition. During this expedition, Walton finds his ship stuck amidst the ice of the North. For him, nature is his enemy. The ice is the one thing which forces his travels to cease. It is nature which holds the power over the man wishing to make a name for himself.
In the end, both Victor and Walton are subject to the power of nature. Nothing is found to be more powerful than nature itself. Outside of the power of nature, the imagination and individual goals of both men prove to be Romantic. That said, it is the power of nature which proves to be the most forceful element in the novel.