Another possible theme could be self - discovery. The boy, being bullied, might start to question who he is. He could be on a journey to figure out if he should change to fit in or stay true to himself. Through the bullying, he may learn more about his own strength and identity, which could be the underlying theme of the story.
It might be about acceptance. The sissy boy is bullied for not fitting into the norm, so the theme could be about society's need to accept people who are different. The boy is probably seen as different because of his behavior or interests that deviate from what is considered 'masculine', and the story could be highlighting how important it is to embrace diversity.
The main message could be about the importance of acceptance. That we should not bully someone just because they don't fit into our narrow ideas of how a boy should be.
Without knowing the exact story, I can only guess that it might be a sad and poignant tale. The 'b' in the title might stand for the boy at the center of it. He could be facing all sorts of bullying, from name - calling to physical abuse maybe. And the story might focus on how he tries to overcome this difficult situation, whether it's by finding true friends who accept him, or by learning to be strong in the face of such adversity.
Perhaps the theme is sacrifice. In many love stories, one or both characters sacrifice something for the sake of their love. In 'b love story', it might be the case too. For example, sacrificing a career opportunity to be with the loved one.
It could also be a theme of mentorship. The black master could be guiding the white sissy, showing that despite their differences in appearance or initial dispositions, they can have a positive and growth - promoting relationship. The master imparts knowledge and wisdom, and the sissy learns and evolves. This emphasizes the importance of cross - cultural or cross - type relationships in personal development.
One possible main theme could be identity. The boy in the story might be on a journey to discover who he really is, especially if he's facing external pressures or expectations that conflict with his true self.
One possible main theme could be transformation. If the boy is somehow related to a stone, perhaps he goes through a transformation similar to how a stone can be shaped over time.
Love could be a theme. Maybe they fall in love despite differences in their backgrounds.
It could also be that the sister is trying to prove a point about gender equality. By making her brother experience what it's like to be a girl, she wants to show that there are no big differences between the two genders. However, this is a rather extreme way to do it.
Another possible theme could be family. The story could be centered around the relationship between the German boy and his family members. It might show how they support him, or how family traditions influence his life. There could be conflicts within the family too, and how the boy copes with them. It could also be about the boy learning important values from his family, like honesty, kindness or hard work.
His character may transform from being self - centered to more community - oriented. In a sissy school, there could be a strong sense of community. The boy would be involved in group activities like choir or gardening. Through these, he learns the importance of cooperation and giving back. He might also become more patient, as the environment in the school encourages a slower, more refined pace of life.