I'm going to assume you're asking about 'The Cinnamon Society' by Kate Racculia, since 'the cinnamon book' rings a bell for that one. The main character is definitely Mia, a teenage girl who’s a bit of a loner and gets wrapped up in this secret society of women that her late mother was part of. Her perspective is the anchor; she's grieving and trying to understand her mom's hidden life. The other key figure is probably Agatha, who runs the society—she's this enigmatic, older woman with a lot of secrets and a kind of fierce protectiveness over the group's history. There's also Mia's dad, whose role is more in the background as he deals with his own loss, and various members of the society who pop in with their own quirky personalities and hints about the past. Honestly, Mia's journey of piecing things together is what stayed with me more than any single side character. The book plays with mystery and family legacy through these characters more than being a huge ensemble piece.
It’s a quieter novel, so don’t go in expecting a massive cast like an epic fantasy. The focus is really on Mia's internal world and her connection to Agatha. If you’re into mother-daughter dynamics and puzzles about the past, you’ll probably find the character work satisfying, even if some of the society members blend together a bit for me. I remember finishing it and wishing we got just a tad more from Agatha's younger years, but that’s probably the point—some mysteries stay within the society.