Love is probably a main theme. It often is in novels with such a title, where characters' relationships are central.
Heartbreak could be another theme. If someone is being'shot in the heart' in a metaphorical sense, it likely involves some form of emotional pain or loss.
Redemption might also be a theme. Maybe the characters are trying to make up for past mistakes or heal from past traumas, which is something that can be associated with the idea of a heart - centered story. For example, a character who has hurt someone in the past may be on a journey to earn forgiveness and heal their own broken heart in the process.
Perhaps the theme of sacrifice is present in 'the heart novel'. Characters may have to give up something they cherish, like a dream or a relationship, for a greater good. And social inequality might be another theme, showing how different characters are affected by the social structure in the story.
Another one might be 'The Fault in Our Stars'. It shares the aspect of dealing with strong emotions and relationships, much like 'shoot me in the heart novel'.
One common theme is the exploration of the relationships between the characters. For example, there might be fanfictions that focus on the romantic relationships that were hinted at or could have developed in the show. Another theme could be the characters' personal growth and how they deal with the challenges in their lives off - camera, so to speak.
One of the main themes is imperialism. The novel shows the dark side of European imperialism in Africa, how it exploited the land and the people. Another theme is the loss of innocence. As the protagonist travels deeper into the Congo, he witnesses so much horror that his own sense of self and innocence is shattered.
One possible main theme could be love. In many novels, love often plays a central role, whether it's romantic love between characters or love within a family or community. Another theme might be the unique Sardinian culture. The setting of Sardinia can bring elements like local traditions, values, and ways of life into the story.
One main theme could be survival. The characters are likely facing extreme conditions at sea, which forces them to fight for their lives.
One main theme could be cultural identity. It might explore how characters in the novel are shaped by their cultural background. Another could be the concept of change, perhaps in relation to the society depicted in the story.
One of the main themes is probably the exploration of human - animal relationships. It shows how humans treat animals and what that says about their own humanity.
Love and sacrifice could be main themes. In many novels, a red heart can symbolize deep love or a passionate spirit, which might lead to characters making sacrifices for their beliefs or loved ones.
Courage is likely a main theme. The title itself suggests that the characters have fearless hearts, so they must be showing courage in different situations.