In Letter II, of Mary Shelley's Frankenstein, Robert Walton admits to his sister that, while surrounded by men, he is alone.
I have one want which I have never yet been able to satisfy; and the absence of the object of which I now feel as a most severe evil. I have no friend.
Robert Walton feels isolated from the rest of the men on the ship because they do not look at the expedition in the same way he does. For Walton, the expedition to the North Pole is one which is a lifetime dream. The hired men on the ship are only motivated by their paycheck. Essentially, the men and Walton have nothing in common.
When the stranger first comes aboard, in Letter IV, Walton is initially astonished at the man.
You may conceive my astonishment on hearing such a question addressed to me from a man on the brink of destruction.
Upon the stranger coming onto the ship, Walton realizes the horrible state the man is in.
I never saw a man in so wretched a condition.
A few days after the stranger comes aboard, Walton reveals his awe of the stranger. Walton is completely intrigued by the man.
I never saw a more interesting creature.
The crew, curious about the man, desired to ask the man questions. Feelings as though he needed to protect the stranger, Walton refused to allow the men near the stranger.
I had great trouble to keep off the men, who wished to ask him a thousand questions.
The conclusion of the August 5th section of Letter IV shows exactly how Walton feels about the stranger.
For my own part, I begin to love him as a brother; and his constant and deep grief fills me with sympathy and compassion. He must have been a noble creature in his better days, being even now in wreck so attractive and amiable.
Essentially, Walton is completely drawn to the stranger. Although he has yet to hear the stranger's story yet, something has drawn him to the stranger. His feelings for the stranger are best described as those similar to brotherly love. Walton wishes to protect, care for, support, and love the stranger.