I quite enjoyed reading this book, and was impressed by its themes and nuance, especially considering that Shelly was just 20 years old when it was published (I only have three more months to come up with something as big as Frankenstein 🤕). The two big messages that I took from reading the book are
1). Human (yes, I know) nature is fundamentally oriented towards compassion and the pro-social. The existence of discrimination, ostracization, and bigotry opposes this nature, thus allowing for cycles of violence wherein everyone is left worse off and further isolated.
2). Scientific ambition ought to be moderated by/met with an obligation to maintain or improve the quality of life of those who are affected by your ambition.
To the first point, I am hard-pressed to think of a character who does not start off supportive and amiable. The only two for whom I feel this characterization is inaccurate are the relatively minor characters of Safie's Father & M. Krempe, one of Victor's mentors who dismissed Victor's passion for alchemy in youth. While the latter character's problem is narrow-mindedness and ignorance, I think of the former as in support of my first claim; it was chiefly bigotry and discrimination that denied his daughter's permission to marry a Christian. As for the other characters, their geniality seems relatively evident. Victor has close ties with his friend Henry Clerval and his family (who are, themselves, all also written as very endearing people). Even towards the end of his life, he is described by Captain Walton as "noble and godlike in ruin." The DeLacey family were described with the utmost praise at first, and only ever saw anger and hostility after giving in to bigotry against Victor's Creation (even though their family had already suffered under similar instincts from Safie's father). Most resonant with me, however, was our encounter with the Creation's nature. He brought firewood to the DeLacey's for the better part of a year, wished to share in their traditions, admired the beauty of nature during summer and spring, helped to save a drowning girl, and described his initial love for humanity. His murderers came only after he was shunned by everyone; they were his means of vengeance, which he reflected on at the end of the book with sorrow and "the bitterest remorse." By no means do I excuse his actions, I merely wish to explain that he, like everyone else in the book, was of a kind disposition, that only saw itself eroded as a consequence of ostracization.
Violence, initially permitted by isolation, became worsened and exasperated under a cycle of retaliation between Victor and his Creation. Like how his Creation destroyed his brother William and friend Justine, Victor destroyed the companion he promised the Creature right in front of his eyes. Though he had other reasons for doing so, I find it difficult not to see this action as somewhat retaliatory. In turn, the Creature destroyed Victor's own companion, and act which we see, at the end of the book, made him miserable. Victor pledged retaliation against the Creature, giving up the little he had left, and the two died alone (which the setting corroborates, both of them near or at the desolate Arctic at their times of death). Walton is there for Victor, of course, though I believe his purpose is more so meant to contrast with Victor's scientific irresponsibility.
To my second point, I believe all the death and tragedy in Frankenstein comes from his failure to be responsible in his scientific practices. There is, of course, the interpretation that Victor merely shouldn't have made his Creation at all, though I don't believe that such a dramatic change would have been necessary. The deaths of Justine, Henry, William, his father, himself, and his Creation were not simply a result of the Creation itself, but instead of his unwillingness to care for it. Since Victor brought the Creature into this world without its consent, he should have assumed the responsibility of a parent that does not neglect their child. The problem wasn't the creation of a being, it was that, after his creation, he would not have "lament(ed) (his) annihilation."
"I remembered Adam's supplication to his creator; but where was mine? He had abandoned me."
Victor's mistake wasn't that he had a scientific undertaking, but instead that he ignored his duty afterwards.
Walton provides the counterexample. His journey to the Arctic was ambitious, though for this alone he would not have been punished. He was never punished, because he recognized his responsibility to his crew, and, under changing weather conditions, recognized his inability to fulfill it within the project. The only check to his ambition was consideration for those affected by it.
Should Victor have made a companion for his Creature? I am inclined to say no; her purpose would have been only to fulfill him. Any complication in the relationship may have meant more responsibility for Victor, who proved himself unable to oversee just one. Though I am conflicted and have gone back and forth on this question