One possible theme could be royalty and power. It might show how the princess deals with the power and responsibilities that come with her title. Another theme could be love, whether it's love for her family, her people, or a romantic love.
One possible theme could be class differences. The princess is likely from a high - class background while the marine is from a more common, military - oriented background.
One possible theme could be creativity. Since it involves a 'yarn princess', she might be creating all sorts of things with yarn, showing off her creative side.
Friendship could also be a theme. Since she can't rely solely on her royal status, she has to make real friends. Through her secret, she might attract people who like her for who she is, not what she is, and these friendships help her in her journey in the 'the secret princess story'.
Another theme could be survival. If it's a story about individuals or a group, they might have been facing challenges and trying to survive in the conditions of 1922, which could include economic hardships, political unrest or natural disasters.
Love is probably a major theme. The prince's search for his princess is centered around love. Another theme could be adventure, as he likely has to go through various adventures to find her.
One possible theme could be courage. The little princess might need to be brave in the face of difficulties.
Another theme might be hope. In a long - drawn - out situation like that of 3096 days, the person in the story must have held on to hope to keep going. And also, transformation could be a theme. A lot can change in 3096 days, and the story could be about how the protagonist transformed over this time period.
One possible theme could be unrequited love. If it's a true story, the person might have had strong feelings for someone who didn't feel the same way.
One possible theme could be faith. Since it's a convent, faith would likely be a central aspect of the story, with the nuns' unwavering belief in their religion being a major part of their lives.
One possible theme could be heroism. The rescuers are often the heroes, showing great courage and self - sacrifice.