This question is especially interesting because Frankenstein’s supporting cast is so often forgotten in favor of attention toward the great brute. Now, there’s a personality/character/identity study!
In the novel, the reader spends a great deal of the time in either Victor Frankenstein’s or the monster’s head. And not only is one immersed in their subjective worlds, but what comes through the Romanticism of the text is Frankenstein’s and his nemesis’s hardwired constitutions. Elizabeth—her expository passage says she is “of a calmer disposition,” which generally squares with the typical image of what a dutiful Victorian daughter should be. Yet, their Alpine home is no tame Victorian garden: she’s a proto-feminist striver and, in some broader way, an Elemental. She’s set up as perhaps not the emotional core, in comparison to the monster, but the outlet for the author’s, Mary Shelley’s, spirit: Elizabeth is in touch with the wild forces of nature and possesses much the same fervor as that which compelled the author’s own literate expression.
“Dark, gloomy” settings are an important factor in gothic literature, the more wild-blown the better. So, chapter 2 begins with character introductions, but also by painting the setting as a backdrop of gothic dimensions and preoccupations: intensity of feeling, or drive and poetic emotion. Victor mentions “The turbulence of our Alpine summers.” And by Victor"s narrative description, Elizabeth is, essentially, his opposite—in terms of his investigative zeal—not to mention in terms of the dormant psychic “violence” in his nature. He has a doppelganger: a symbiotic, evil twin, yes, but Elizabeth is his opposite within an emotional pair-bond.
Henry Clerval, in his description (returning to my observation about how Shelley’s sensationalistic prose matches the tone and tenor of gothic literature) is a man in his prime, wishing to become “as the gallant and adventurous benefactors of our species,” with no less a role model than King Arthur, and with the esprit de corps of the Round Table. He provides that optimistic, British-Empire manliness and grit.
To get back to Victor, however, a doomed Romantic seeker, he’s the manic catalyst of the destructive plot. When things go wrong in the gothic novels (Frankenstein was first published in 1818), everything goes straight to the devil. A gothic novel is a scandalous tale told in graphic detail: shock effect would be very much the point. One example of foreshadowing in the early section of the novel is the difference between the rapture of Victor's thoughts prior to the creation scene and after. Victor's narrative flights cover extreme contrasts of beauty and revulsion. And, in terms of contrasts in behavior, Henry is Victor’s counterweight. Nonetheless, Victor Frankenstein is isolated from the humanity of his friends and his creation.