How does Robert's desire for a friend affect his relationship with Dr. Frankenstein?

The novel opens with Robert Walton writing to his sister at length about his lack of a friend as he embarks on his voyage. He tells her of his deep desire for friendship. He writes:

I bitterly feel the want of a friend. I have no one near me, gentle yet courageous, possessed of a cultivated as well as of a capacious mind, whose tastes are like my own, to approve or amend my plans. How would such a friend repair the faults of your poor brother!

Robert then writes to Margaret four months later to tell her of the extraordinary occurrence of meeting Victor Frankenstein. Robert finds Victor a "divine wanderer," "wonderful," and a person of "extraordinary merits." Because of their similar class background, education, and sensitivity, Robert considers Victor a kindred spirit. He writes:

Sometimes I have endeavored to discover what quality it is which he possesses that elevates him so immeasurably above any other person I ever knew.

Robert's loneliness and longing for friendship cause him to exalt Victor into more than he is. This encourages him to see the best in Victor and to credit him with more discernment than he actually has. Walton is a very sympathetic audience, prone to liking and accepting Victor, and eager to hear all the details of his story. We know that in Robert's hands, Victor will be shone in a positive light despite his story of ambition and pride.

At the start of Shelley's Frankenstein, we meet Robert Walton through the letters he is writing to his sister. Walton describes his ambitious plan to explore the North Pole. Then, along the way, he and his crew pick up a man who is distraught and near death. The man is Victor Frankenstein, and he proceeds to tell his life story to Walton. We learn through Walton's commentary about Victor that he is sympathetic with Victor's story. His admiration for Victor and his compassion for this shell of a man make Robert Walton less likely to judge Victor's actions and more susceptible to be won over to his side of the story.
As we know, Victor's story is that of his creation of a creature from dead body parts and the subsequent tragedies that action brings upon Victor and his family. Hoping for fame and glory, Victor does not think ahead about the responsibilities he will have for his creation, and he is disgusted when he brings it to life. He abandons the creature to learn how to function in the world as though it is a newborn abandoned by his parents. Later, when the creature makes an articulate appeal to his creator for a companion, Victor hesitates but agrees, then later destroys the creature before bringing it to life. This unleashes the monster's revenge.
When Walton meets Victor, he and the creature are chasing each other around the North Pole in an apparent fight to the death. Walton reflects compassionately on Victor's story and even considers Victor's request that he carry out Victor's revenge against the creature. When the creature shows up and Walton sees the complex emotions involved on his side of the relationship, Walton perhaps becomes sympathetic to the creature. Even though Walton is hesitant at first to criticize Victor in any way, feeling a close kinship to him, he eventually turns back with his crew, electing to preserve its safety at the cost of his own personal ambitions. Apparently, he has learned something from Victor's story. However, his friendship with Victor does make it difficult for Walton to judge Victor outright, despite the feeling most readers have that Victor acts unethically throughout the novel.