In Frankenstein, what does the monster do when the DeLacey family moves away?
When the DeLacey family moves away, the monster reacts first with despair, then with rage. His immediate reaction is to return to his "hovel" in "a state of utter and stupid despair." It is at this point that he first experiences "feelings of revenge and hatred," which he at first directs solely at the DeLaceys, whose departure is the immediate cause of his suffering, but which eventually grow to include a wider focus for the untenable situation in which he has been placed. The monster reflects that the DeLaceys have "spurned and deserted [him]," and, admitting that his behavior evidences "a kind of insanity in [his] spirits that burst[s] all bounds of reason," he gives vent to his initial fury by first destroying their garden, then burning down their cottage.
The monster then quits the scene of his perceived betrayal, and sets off to wander, but he knows that he will be "hated and depised" wherever he goes; "every country must be equally horrible." Finally, in desperation, he concludes that only Victor, his creator, can change the miserable condition of his existence, and resolves to find him, and to convince him to create another being like himself, so that he will have a companion to assuage his loneliness (Volume 2, Chapter 9).