
Theory Acotar 6 and 7
I think Sarah is going to send Elain and Lucien somewhere outside the Night Court along with others (maybe Vassa and Jurian), and that’s when their development will begin. I feel the same way about Gwyn and Azriel, though I’m not sure if they’ll stay on a mission within the Night Court or head elsewhere.
I also think the shift in power mentioned in the synopsis will involve Eris taking his father's place and Tamlin losing his position in the Spring Court. The betrayal could center on Lucien and Helion discovering their family bond, or someone in the Inner Circle hiding something (such as a partnership or a piece of information). Or even a character hiding another one.