Hostage of Empire, book 1: The Throne of the Five WindsS.C Emmett2019

Two queens, two concubines, six princes.
Innumerable secret agendas.
A single hidden blade.

The imperial palace -- full of ambitious royals, sly gossip and unforeseen perils -- is perhaps the most dangerous place in the Empire of Zhaon. Komor Yala, lady-in-waiting to the princess of the vanquished kingdom of Khir, has only her wits and her hidden blade to protect herself and her charge, who was sacrificed in marriage to the enemy as a hostage for her conquered people's good behaviour, to secure a tenuous peace.

But the Emperor is ageing and the Khir princess and her lady-in-waiting soon find themselves pawns in the six princes' deadly schemes for the throne -- and a single spark could ignite fresh rebellion in Khir.

Then, the Emperor falls ill -- and a far bloodier game begins...