Circe is a fantastic novel. The story sits with you and finds its way into your thoughts when you don't expect it. I always found myself looking forward to reading it.
There are too many themes to look into, but there is one that I think sells itself: the relationship of women to men. Circe's relationships with three women are explored, but none as thoughtfully and continually as her relationship with her father, her brother, her various lovers, and pigs.
Each of these relationships is characterized by the explicit or implicit hierarchy that Circe accepts- the man is above the woman. She accepts this, time and time again, and is wounded in all the ways a person can be wounded. Why does she accept this? It's always been that way. Literally, since she's thousands of years old.
Better question: why do the men also accept this? Helios- well, he's literally the sun, so that's at least not unreasonable. Numerous Greek heroes treat her like shit though, and they're not gods at all. What they have in common isn't just run-of-the-mill narcissism (though they have that in spades), it is that they each see themselves as the heroes of their own stories. Their shitty behavior is enabled by controlling the narrative.
Of course, that's the point of the book: Circe is a retelling of a few Greek myths but namely The Odyssey from Circe's perspective.
This is the lesson for men who read Circe then: you are not the main character of the story; do not act like it; do not treat women like accessories to it. This lesson extends to women too but with slight adjustment: Do not let another person (especially a man) control your narrative; do not submit to be a footnote.*
A lesson for everyone: co-write a narrative with mutual respect and admiration without being dominating. The book is not a list of Circe being constantly abused-- she does damage in her own way. Those relationships that she and others attempts to dominate slip into rage and fear. Those that she submits to end with her being hurt. Those that involve a mutual, separate respect are those that ultimately redeem her.
Of course, Circe has a bunch of other themes like parenthood, a more powerful look at femininity than I am qualified to write about, and the question of "meaning and death." They are all worth reading this novel to think about.
*Obviously both lessons apply to both/all genders, but the historical precedent is for the lessons to be gender biased.