As he departs for England with his friend Henry, hoping that the presence of Henry will prevent the intrusion of the dreaded creature, Victor is anxious about his "friends" who are not aware of the existence of "their enemy." They would, thus, be vulnerable to the creature's attacks if he becomes "exasperated" by Victor's departure.
Victor's use of the word "friends" includes his family and Elizabeth. Victor reasons that the creature will follow him because this monster has promised to pursue him no matter where he goes: "But he had promised to follow me wherever I might go; and would he not accompany me to England?"
Yet, while Victor surmises that the creature may wish to make certain a mate is made for him and follow his creator, there is also the possibility that the creature might remain behind and prey on those Victor loves. Since his loved ones are unaware of the existence of this enemy, and are unprotected from attacks of such a creature, Victor is greatly disquieted, and he feels much uneasiness about his family's safety. Victor describes himself as "agonised" with the idea of the possibility of harm to those loved ones that are yet part of his family after the recent tragedies.