What request does the monster make of Victor that he promises, if granted, will ensure he will leave Victor and his family alone?

In the novel Frankenstein, the monster requests that Victor create a mate for him in exchange for the monster leaving Victor and his family alone. When the monster escapes from Victor's laboratory, he finds a very lonely world into which he has entered. People flee from him, and he watches a family who demonstrates companionship and love. While watching, the monster begins to find a deep sorrow inside of himself due to his loneliness and inability to live among the public successfully. He meets Victor and makes a pact that if Victor creates a mate for him, he will not harm Victor or any of his family. In a state of panic, Victor agrees to this in order to ensure safety for him and his family. Victor does not think about the consequences of a second creation. He believes the monster will stay true to his word, so he makes arrangements to create a second living creature as a mate for the monster—but later changes his mind.