Im not quite sure if im mixing up two different books together, but i remember this one scene, where an older lady (an elite) is pretending to be good but is in fact evil, she puts these bracelets on the mc girl which forces the girl to do exactly as she is told against her will. As a demonstration of this power she forces the girl to lick the feet/sandal of her son(s?). Otherwise she leaves the girl to work with her servants.
Im fairly certain the girl is friends with a dragon, a young one who cannot fly very far or cannot carry her far.
I think she met the evil lady in a secluded or secret area where she was being taught magic before she was enslaved.
I believe the girl is part of a prophecy including the dragon friend.
Unfortunately this is all I can remember due to how i remember questioning the slavery part in what im sure was otherwise a children's book. (just seemed a bit more explicit than i was expecting)