The monster explains how this happened in chapter 16 as he reflects upon how those events transpired. Initially, he did not seek to harm the young William, whom he describes as a "beautiful child" who disturbed the creature 's rest as he sought respite from mankind in those early...
The monster explains how this happened in chapter 16 as he reflects upon how those events transpired. Initially, he did not seek to harm the young William, whom he describes as a "beautiful child" who disturbed the creature's rest as he sought respite from mankind in those early days. As he watched William, he believed that he was too young to have been prejudiced by the world and that he could thus train William's young mind to accept the deformities of the monster, thus building a natural friendship with the boy. Instead, when confronted, William screamed in horror and called him a "monster" and threatened to tell his father, Mr. Frankenstein.
This name incited an inner rage within the creature, and he acted swiftly, grabbing young William around the neck and killing him quickly. Instead of looking upon this murder with regret, which might suggest a being capable of developing a moral compass, his heart swells in "hellish triumph," thrilled that he, too, can create desolation.
The murder of William, then, is partially directed at inflicting pain on Victor Frankenstein but also originates from a quick and deep rejection from an innocent person whom the creature feels is his best bet for acceptance. He feels that if a young child, too young to have been taught the world's prejudices, cannot accept him, he is doomed to a life of alienation, and he will thus inflict as much pain upon this world as possible.
He frames Justine for the murder because he sees her as "one of those whose joy-imparting smiles are bestowed on all but me." Justine embodies a joy reserved for everyone human, and the monster sees in her all the rejection that he will face. He frames her simply because he seeks destruction, and he realizes that he has the power to accomplish it. He wants to see her suffer because he suffers. Justine is framed because she symbolizes the joy of mankind which the monster realizes he can never know.