Rosalind grapples with the aftermath of being betrayed by someone she trusted implicitly. This betrayal has shattered her world and left her emotionally scarred. As she fights to save Orion and protect Shanghai, Rosalind also embarks on a personal journey of healing and learning to trust again.

Orion's memory loss becomes central to the narrative. Stripped of his past, he is a stranger to Rosalind and himself. This theme explores how our memories shape our identities and influence our present and future actions. The novel delves into the potential for regaining lost memories and the complexities of rebuilding a sense of self.

Set against the backdrop of impending war, 'Foul Heart Huntsman' examines the difficult choices individuals must make when personal desires clash with national duty. Rosalind's love for Orion is undeniable, yet she is also fiercely loyal to her country. The novel explores the sacrifices made in the name of love and patriotism, forcing characters to confront impossible dilemmas.