Since I don't have access to 'The First Commandment BL Novel', I can only guess. BL novels frequently explore themes of longing and unrequited love. There could be themes of loyalty and betrayal as well. Also, the idea of coming of age and how the characters' understanding of love and relationships evolves as they grow is often a part of BL novels, and perhaps this one is no exception.
As I'm not familiar with this particular novel, it's difficult to say. However, common themes in BL novels can also include social issues such as homophobia and how the characters navigate through a society that may not be fully accepting. Maybe 'The First Commandment BL Novel' also touches on the power dynamics in relationships, as some BL novels do.
Well, without more details about 'The First Commandment BL Novel', it's a bit hard to give exact similar ones. However, 'Yuri!!! on Ice' (although it's more of an anime with strong BL undertones) inspired a lot of BL - like fanfiction. Also, 'No. 6' is a great dystopian BL - ish story that might be of interest if you like complex world - building and relationships.
Again, without more details about this particular novel, it's hard to say. It could potentially be about loyalty, obedience, or some moral code if it's related to the idea of a 'first commandment' in a religious or ethical sense.
One of the main themes is probably the struggle with unrequited love. Often in BL novels, one character may have feelings for another who is initially unaware or hesitant.
Love and passion are the main themes. It shows the intense feelings between the characters.
Another theme could be self - discovery. The characters often grow and learn more about themselves through their relationships. For example, they might discover new aspects of their personalities or their desires in life.
Another theme is justice. The characters strive to uphold justice in a world full of challenges and corruption. They fight against the wrongdoings and try to make the world a better place.
Love against all odds could be another theme. In a BL context, the two male characters falling in love in a situation where they might face external opposition or internal doubts due to their initial enmity. It may also explore themes of self - discovery as they navigate their relationship.
Love is a main theme. It shows different forms of love between the male characters.
One of the main themes is love and acceptance. The characters learn to accept their feelings for each other in a society that may not be fully accepting of same - sex relationships.
Fate could be another theme. Since the red thread is associated with fated connections, it may suggest that the characters' relationship in the novel is pre - determined in some way.