Elizabeth Lavenza Frankenstein is the adopted sister of Victor, which he considers as his cousin. She is a lively and joyful person that displays unconditional affection to her surroundings. She was raised and educated by the Frankenstein family, and after the death of Justine Moritz, she takes on the maternal tasks of the family. Furthermore, while Victor is in Ingolstadt, she writes to him regularly. She is the only way Victor gets information about his family.
Eventually, once Victor’s mother dies of scarlet fever, Victor is forced to come back in Geneva. Victor’s father, Alphonse, then asks him if he would want to marry Elizabeth (Victor’s parents had this plan in mine since they adopted Elizabeth). He accepts, to the great joy of Elizabeth. However, because Victor ends up destroying the female creature he was preparing for his Monster, the Monster decides to murder Victor’s wife during their honeymoon.
Interestingly enough, Elizabeth Lavenza is a lot different from one adaptation to the other. In the 1831 edition of the novel, Elizabeth is rescued by Victor’s mother from a peasant cottage in Italy. In the 1931 movie adaptation, Elizabeth has no familial relation with Victor, and she is Henry Frankenstein’s fiancée (which is the adaptation of the original Victor Frankenstein). In the 1994 horror drama adaptation by Kenneth Branagh, Elizabeth is described exactly as in the original adaptation by Mary Shelley, but one important point differentiates them. In the horror movie, Victor Frankenstein succeeds in bringing her back to life with the same technology he used on his Monster. However, she is so ugly after her reanimation that she decides to commit suicide.