can't stop thinking about how heterosexuality in frankenstein is continuously characterised as something both enforced externally and incestuous.
victor has been brought up and groomed to marry his cousin—who is essentially his sister—by his own parents, and throughout the novel never proclaims any actual romantic or sexual attraction to her, it's just accepted as a basic fact of his life that he will marry elizabeth; and since his fondness and admiration for her are unquestionable, why shouldn't he?
the creature doesn't seem to make any difference in its feelings towards men and women initially ("Felix seemed ravished with delight when he saw her [...] his eyes sparkled, as his cheek flushed with pleasure; and at that moment I thought him as beautiful as the stranger." ) but only learns from his observation of the family and the books that constitute his introduction to the world that it's a female companion he's supposed to desire, and blackmails victor into making him a sister-wife of his own.
that very project then becomes the pretext for victor to elude his own incestuous predestined marriage and flee into the homo-social union with his best friend henry clerval once again.
his eventual wedding to his sister/cousin is also invariably treated by his parents as a kind of ultimate solution to unhappiness, an unhappiness that is brought into victor's world by his queer desires (to bring forth life like a woman might, to bear a child without a wife) and the subsequent abjection of the consequences of the fulfillment of that desire in a world that cannot hold it, leading to the deep repression and self-loathing that manifests itself physically as the fever that almost consumes him—but does not, solely for the care of his beloved and devoted friend henry.
clerval and walton are also the only characters in the book victor doesn't feel indebted to in some way, and who don't treat his mental illness as some annoying hindrance to their own contentment (maybe a harsh criticism of victor's family, i do think it's obvious they care for him genuinely, but they also push him further into isolation by continuously pressuring him to finally 'be glad' again for their sakes), or make their own happiness dependent on his actions in some way (as the creature does, even if rightfully so).
that perceived debt is also always incestuous in nature. he owes his family cheerfulness as well as—when it comes down to it—sex with his sister, he owes his "son" (and external manifestation of his own repressed queerness) the fulfillment of his sexual desires (even though it's of course in actuality an antidote to his solitude first and foremost, the fact that he is supposed to make him a bride still carries the same sexual undertones). only in his male friendships that are very heavily queer-coded and free from both familial ties and heteronormativity is victor truly free to just...be.
homoerotic love is also at multiple points associated with a deep adoration of the natural world (walton about victor: "Even broken in spirit as he is, no one can feel more deeply than he does the beauties of nature. The starry sky, the sea, and every sight afforded by these wonderful regions, seems still to have the power of elevating his soul from earth. Such a man has a double existence: he may suffer misery, and be overwhelmed by disappointments; yet when he has retired into himself, he will be like a celestial spirit, that has a halo around him, within whose circle no grief or folly ventures." / victor about clerval: "Clerval! beloved friend! even now it delights me to record your words, and to dwell on the praise of which you are so eminently deserving. He was a being formed in the ‘very poetry of nature.’ His wild and enthusiastic imagination was chastened by the sensibility of his heart. His soul overflowed with ardent affections, and his friendship was of that devoted and wondrous nature that the worldly-minded teach us to look for only in the imagination. But even human sympathies were not sufficient to satisfy his eager mind. The scenery of external nature, which others regard only with admiration, he loved with ardour." ) and becomes therefore itself connotated as natural (as opposed to the heterosexual love that relies on artificial enforcement).
but by externalising and rejecting his own queerness in the form of creating and then immediately abandoning the creature, he tarnishes this refuge, turns it into something both incestuous and heterosexual once again (incestuous because he makes his desire into a son to cut it out of himself, heterosexual because his creation demands a wife of him). when he finally refuses the creature's request, it promises him: "I shall be with you on your wedding night." it really couldn't be made more obvious. "On that night he had determined to consummate his crimes."
victor is also again and again presumed by his family to be tormented because he "might love another", both his father and later elizabeth herself pose this question to him. and in a sense, they're right (if we read victor as being romantially interested in clerval)—but in another sense, more importantly, and through the same queer lense, they're wrong. because they're not asking about love, not really; they are asking about heterosexual love specifically, implicitly, and the cause of his misery is decidedly not that he is in love with a different woman; but something he can't even speak of, something he must keep from the ones closest to him at all costs, which distances him further and further from everyone he cares for.
only when she's dead does victor ever truly yearn for elizabeth, but in death she furthermore becomes almost merged with clerval, both of them unified into that amalgam of loss and grief for what has been taken from him. the fact that his father and his brother wiliam aren't part of this mourning ritual seems to only further validate clerval's position as having been just as much a romantic prospect as elizabeth, who has in her altered state of unavailability now also become a somewhat queered desire for victor.
in the final paragraph of the novel, in its last and only conversation with walton (which arguably serves as a confession), the creature admits to having been so overcome with remorse and pity after having taken clerval from victor that he felt ready to let go of his plans of further revenge—until it was revealed to him that victor was still going forth with his plans to marry elizabeth. this final submission to heterosexual bliss is what seals their fate, what the creature cannot let stand. and in the end, all that is left of victor frankenstein is what he could not let himself love.