Psychoanalysis focuses on unconscious desires, dreams, and aggression by sons and fathers. Also, Freud's three-part struggle between id (pleasure principle), ego (reality principle), and superego (morality principle) is personified.
In Frankenstein, we have many conflicts between Victor and the Monster, his "son," indicative of an Oedipal Complex. Both are competing to have a mate and mother. However, Freud says that sons have an unconscious desire to kill their fathers; in the novel, the Monster's desire for revenge and a mother-mate is expressly real.
Also, there are characters who play the roles of personality:
- Clerval is the "ego," the rational side to Victor's "id." Enotes says:
Victor's closest friend and companion, who balances his emotional and rational pursuits. He studies Oriental languages but passionately loves nature and life. Victor acknowledges that "[H]is wild and enthusiastic imagination was chastened by the sensibility of his heart." And unlike Victor, who wishes to learn "the secrets of heaven and earth," Clerval aspires "to become one among those whose names are recorded in story as the gallant and adventurous benefactors of our species."
- Alphonse, Victor's father, plays the role of "superego." Enotes again:
Victor's father is described by his son as "respected by all who knew him for his integrity and indefatigable attention to public business."
- The Monster, obviously, plays the role of Victor's "id." In fact, it is "id" incarnate, literally his dark-side doppelganger who haunts him throughout the second half of the novel.
So, overall, the novel can be read as mankind's struggle between reason (ego, superego) and irrationality (id), between light (ego, superego) and darkness (id), between public (ego, superego) and private (id), and between community (ego, superego) and individuality (id).