Throne of the Switched Phoenix

Elara, who rules the Phoenix Clan, saved her husband Adrian's life. Adrian and her half sister Lilith went behind her back afterwards, and they swapped Elara's daughter for a daughter Lilith had outside the marriage. Elara's daughter grew up as Elysia, loved and looked after, and in time she was named heir. The other girl, Morrigan, was raised by her birth mother, who mistreated her and used her for her own ends, and Morrigan went to the dark arts. Sixteen years on, the swap was uncovered. Adrian and Lilith were arrested once the plot was traced back to them, and Morrigan's parentage came out along with it. The Wolf Clan attacked around then, and Morrigan used a forbidden technique belonging to the Grey Feather Clan to drive them off, which put military power in her hands. Elara gave Elysia the running of the court and gave Morrigan the fighting outside it. The two of them are supposed to be holding the country steady together, with the conflict between them going on underneath.