Just finished rereading the collection again last week, and honestly, the framing story trio is what sticks with me most. The whole thing hinges on Scheherazade, the king Shahryar, and her sister Dunyazad. Scheherazade's the heart of it, obviously, telling a new story every night to save her own life and all the other women in the kingdom. It's her cleverness that drives the entire book. Shahryar's the one she has to win over, this king driven mad by betrayal. And Dunyazad's there in the bedroom every night, the perfect audience asking for 'another story' to keep the chain going.
But calling them the 'main characters' feels a bit off, because the book is really a nesting doll of tales. Within Scheherazade's stories, you get legendary figures like Aladdin, Ali Baba, and Sindbad the Sailor, who are the leads of their own nested adventures. They're so iconic they often eclipse the frame narrative in popular memory. Still, without Scheherazade stitching it all together with that life-or-death urgency, they'd just be a bunch of disconnected folk tales. The real main character might be the act of storytelling itself.