Kyran had a reason for not killing Lira at once.
If Haylee had complete control over Lira, Kyran would not hesitate to kill her. But when his domain passed through her body, he discovered she was not marked. Meaning Lira was purely acting on her own judgment and accord and was not influenced by Haylee's mark.
It then led to Kyran questioning Lira why she went after the emperor.
Due to Cyneah's vision, Kyran and True Void knew Haylee did not order Lira to attack the emperor. Haylee did give Lira permission to act however she saw fit if the emperor did something, but that did not mean the former did not have any influence over the latter's decisions.
Decisions made by a marked person would be greatly influenced by the person who marked him or her.
But since Lira was not marked by Haylee, Kyran was curious why Lira would still prioritize the Crown Princess's will rather than the Emperor.
