Victor describes him as an only child, "the son of a merchant of Geneva, an intimate friend of my father. He was a boy of singular talent and fancy" (1.1.5). Clerval is almost a family member in the Frankensten household: when Victor complains that "My brothers were considerably younger than myself," he notes, "but I had a friend in one of my schoolfellows, who compensated for this deficiency" (1.1.5), and Victor includes Clerval in his account of his "domestic circle" because "he was constantly with us" (1.1.6). The two are united by "the closest friendship" (1.1.5, 1831 edition).
After parting from Clerval on his departure for Ingolstadt, Victor does not see his friend until after the creation of the Creature: he arrives just in time to care for Victor in his first insane fever (1.4.4 and 1.4.7).
After Frankenstein's recovery, Clerval convinces his father to allow him to join Frankenstein at the University, studying classical and Eastern languages:
Clerval was no natural philosopher. His imagination was too vivid for the minutiae of science. Languages were his principal study; and he sought, but acquiring their elements, to open a field for self-instruction on his return to Geneva. Persian, Arabic, and Hebrew, gained his attention, after he had made himself perfectly master of Greek and Latin.In the 1831 edition, this course of study is significantly altered in its purpose:
He came to the university with the design of making himself complete master of the oriental languages, as thus he should open a field for the plan of life he had marked out for himself. Resolved to pursue no inglorious career, he turned his eyes toward the East, as affording scope for his spirit of enterprise.Much later, Clerval accompanies Frankenstein on what is to be a two-year tour of Europe (3.1.4). The two part in Scotland, when Victor begins work on a mate for the Creature. After he destroys his new creation, Frankenstein is arrested for the murder of Clerval (3.4.3), apparently killed by the Creature as punishment for Frankenstein's unwillingness to complete his work.