Kushiel’s Justice is ultimately a poor read because the main conflict revolves around the dubious plot device of prophecies. When the druid Morwen sees a vision of the future which tells her that Prince Imriel’s son will conquer her country and wipe out her people, she reacts in the most stupid and contrived ways possible.
First, she decides to mind-control and rape Imriel so she can get pregnant with his daughter who will somehow serve as a “balance” for his evil future son. When she fails to do that, she simply has another druid transform into a bear to snap Imriel’s pregnant wife’s neck. According to Morwen, these are the only two ways her son will not be born to conquer Alba…but in other stories, something as simple as killing a butterfly from the past could result in you never being born, so how are we supposed to accept Morwen’s explanation?
Even if Morwen had good reasons for deciding that infanticide is the only option, later books show that she and her kind can transform plants and turn invisible. So why doesn’t she try a subtler method of killing the boy, like putting poisonous plants in his food or sneaking into the palace to smother him in his sleep? Morwen and her accomplice, Berlik, go out of their way to make sure Imriel knows that the Maghuin Dhonn druids killed his wife and unborn child, even though that puts Morwen’s people in the very danger she was trying to protect them from since it now gives them the reputation of murderers.
Imriel’s reaction to the murder also makes little sense. He decides that the death of his wife and child is punishment for him not “following his heart” and making a political marriage instead of a love-match. This feels like a very ham-fisted and shoe-horned message because his family died not because he didn’t follow his heart, but because two druids acted stupid.