Hiiiii! You always have the best theories about the next books. Tell me why you think Elain and Lucien will be the focus and any theories you have on how the four parts will be divided.
Ahhh what a big, complicated question but I will do my best to answer them 👌🏼
Why Elain and Lucien Will Be Next
For me, the plot threads laid down in ACOSF trump the ones hinted in the HOFAS crossover due to their language of urgency. I have gone in extreme detail with examples in this older post here for anyone curious. The crossover will be a big deal eventually, but the issues brought up in HOFAS don't need to be dealt with immediately. However, the issues brought up in SF do need to be dealt with immediately. Just look at the way these are worded:
“Tell my Vassa I’m waiting.”
“He should have asked someone before coming here how much time remained before Vassa would be forced to return to the continent—to the sorcerer-lord at a remote lake who held her leash.”
“I can delay my father from allying with Briallyn and starting this war for a little while. But not forever. A few months, perhaps.”
“With a new war possible and Briallyn up to her bullshit with Koschei, we need a strong ally. We need the Spring Court’s forces.”
“He [Beron] did not invite me to accompany him, or explain what he discussed with Briallyn. I can only assume the fallout is approaching, though, and wanted to warn you. It was not something I could risk putting in writing. But for now … for now, it seems as if the world is holding its breath.”
She is very heavy handed in her foreshadowing. Spring, Koschei, and Beron NEED to be addressed now and who is the most interconnected to these plots??? Elain and Lucien.
Theories On How The Four Parts Will Be Divided (Or, the Four Movements = Elucien)
If it is truly an Elucien book, the Four Movements will be a re-telling of the Firebird ballet (credit for this big brain realization to @juriansgeneralgoods who pointed it out)
The Four Movements of the Firebird Ballet have been outlined as:
Part 6 - Introduction, dark and mysterious, the firebird pleads for her freedom from the evil sorcerer koschei
Vassa will be captured, Elain will hold the key via her visions, we get glimpses into the past through her powers, hence why the covers are gray and why one website tagged this book as gothic romance...i foresee everything with koschei being a bit on the creepy side which fits perfectly with the ballet's first movement
Part 7 - Fast Movement, musically more romantic, prince ivan meets a captive princess in her enchanted garden and they fall in love
We will see Elucien's love story truly begin. Perhaps a bargain or a deal is struck in her garden, but they will work together to free the girls / Vassa trapped in the lake under Koschei's control. This could also take place in the Spring Court, fitting with the enchanted garden themes as well.
Part 8 - Slow Movement, brutal and aggressive music, ivan tries to free the princesses but koschei's monsters attack, the firebird helps with her magic feather
My guess is that Beron will act as Koschei's "monsters" in this retelling since we already know he is in the process of allying with him. Danger and battle will face Elucien as they tackle the High Lord of Autumn.
Part 9 - Finale, a lullaby, a victorious celebration, koschei's soul is destroyed
Elain and Lucien will find the onyx box and kill Koschei by destroying whatever is inside, effectively freeing the girls and Vassa from his hold. Their celebration will come in the form of a wedding and/or mating bond acceptance.
When reading about the Firebird ballet, the plot is very evidently a retelling of the famous folk tale, all the way down to Koschei, the captured firebird, the soul in a box, the captured princesses, and the prince. We know SJM is a fan of the ballet AND fairy-tale tellings from previous, older interviews.
If you don't believe me, this is her old bio from 2012 from an old interview:
[Image: "Over the years, she’s written several other novels (most of them fairy-tale retellings), and when she’s not busy writing, she can be found geeking out over things like Han Solo, gaudy nail polish, and ballet."]
To me, the Four Movements is in reference to the ballet/Koschei fairy tale. Something she is a massive fan of and has clearly set up to tell her own version in these next books.
Thanks for this great question!