Frankenstein has destroyed the bride he had built as a companion for the creature. Now the creature wants Victor to experience the same pain and loneliness that has befallen him.
In chapter six of volume three, the creature kills Elizabeth to revenge himself on Frankenstein.
When Victor sees that Elizabeth has been murdered and then the ghoulish, smiling face of the creature, he realizes what has happened. After a period of grief and madness, Victor recalls all the losses that have piled up on him due to the creature. He decides he wants revenge, thinking:
As the memory of past misfortunes pressed upon me, I began to reflect on their cause—the monster whom I had created, the miserable dæmon whom I had sent abroad into the world for my destruction. I was possessed by a maddening rage when I thought of him, and desired and ardently prayed that I might have him within my grasp to wreak a great and signal revenge on his cursed head.
Victor informs a Genevan magistrate of what has happened, is discouraged from hoping the monster can be captured by the police, then goes himself in pursuit of the creature.
In chapter seven, Victor gains strength and the determination to go by dwelling on the revenge he hopes to wreak on the creature:
I was hurried away by fury; revenge alone endowed me with strength and composure; it moulded my feelings and allowed me to be calculating and calm at periods when otherwise delirium or death would have been my portion.
Revenge becomes the central motivating force in Victor's life, one that saves him from madness or death. It gives him purpose when so many he loved have died. He equips himself to pursue the monster and then falls to the ground calling on the spirits of vengeance to help him succeed with his task. Much of his humanity lost, Victor chases the monster everywhere and grows angry when the creature taunts him with signs that Victor has just missed him. Victors states:
Scoffing devil! Again do I vow vengeance; again do I devote thee, miserable fiend, to torture and death.