The answer to this question can be found in Chapter 2, which is when Henry Clerval is first introduced to us. Clerval is presented as a foil to Victor, as he is very different in a number of key areas, especially in terms of his interests and how he devotes his study time. Whereas Victor, my his own admission, devotes himself to learning "the secrets of heaven and earth," and the "metaphysical, or... the physical secrets of the world," note how the text describes the academic pursuits of Henry Clerval:
Meanwhile Clerval occupied himself, so to speak, with the moral relations of things. The busy stage of life, the virtues of heroes, and the actions of men, were his theme; and his hope and his dream was to become one among those whose names are recorded in story, as the gallant and adventurous beenfactors of our species.
The difference is stark. Victor is obsessed by penetrating the secrets of nature with a fury and a violence that he himself recognises. Clerval, on the other hand, wishes his study and work to benefit humanity rather thanbe something that will gain himself glory and honour. We can see through the languge used in this section of the novel that from the very beginning, Victor's obsession lacked moderation and had questionable motives, and this is something that is highlighted by Clerval's approach to his studies.
Clearly a foil to the science-oriented Victor Frankenstein, Henry Clerval possesses all the qualities of a male friend in the Romantic period.
Whereas Victor Frankenstein inquiries are directed to unlocking the physical secrets of the natural world, Clerval occupies himself with things more spiritual:
The busy stage of life, the virtues of heroes, and the actions of men were his theme; and his hope and dream was to become one among those...recorded...as the gallant and adventurous benefactors of our species. (Ch.2)
Whereas Victor flees from his creature after he is frightened by its ugliness, and takes no responsibility for his creation throughout the narrative, Henry assumes the care of his friend Victor and nurses him back to health, staying by his side as a protector.
Moreover, in contrast to Victor, Clerval balances his emotional and intellectual pursuits, but Victor focuses solely upon "the secrets of heaven and earth." Henry desires "to become one among those whose names are recorded in history as the gallant and adventurous benefactors of our species," but Victor's desires are purely selfish. In further contrast, Henry Clerval is sanguine in nature, kind, patient, and loving, while Victor Frankenstein is retributive in nature, antagonistic, impulsive, and selfish. Victor projects much of the blame for the deaths of his family upon the creature, rather than taking responsibility for what he himself has created.