Power plays a crucial role in the development of the key relationships in King of Battle and Blood, and this dynamic can be seen both in Isolde’s fraught interactions with Adrian and in her various power struggles with her father and Killian. Isolde’s distaste for Killian stems not only from their passionless romantic encounters but also from Killian’s persistent attempts to control her. For example, when he tries to force her to return to the castle just after the vampires’ arrival, she tells him, “I outrank you, Commander. It is not within your power to tell me what to do,” to which Killian replies, “No, but it is within your father’s” (3). This tense exchange illustrates Killian’s tendency to fall back on the king’s political power whenever his own influence fails, and St. Clair uses this scene to emphasize that Isolde is caught within a complex patriarchal power structure jointly authored by her father and her former lover. 

Within Isolde and Adrian’s relationship, however, the power dynamics take on a far more nuanced role. At the very beginning of their romantic relationship, Isolde struggles to understand why Adrian seeks to marry her, and because of the complexity of the truth, he declines to answer fully, telling her only, “I set out to become king of Cordova […] And I need a queen” (41).