The main themes in High School DxD novels are power struggles. Different groups, such as the devils, angels, and fallen angels, are vying for power. Romance is also a big theme. Issei has his harem of girls, and his relationships with them are an important part of the story. And there's the theme of self - discovery. Issei is constantly learning about his own abilities and his place in this supernatural world.
The main themes include the struggle for power. Issei is often in situations where he has to fight for his place and power in the supernatural hierarchy. Additionally, friendship and loyalty play important roles. His friends, both human and non - human, support him in his adventures, and he in turn is loyal to them. And of course, there's the overarching theme of the coexistence of different supernatural beings in a world that is not always friendly to such coexistence.
One of the main themes is the supernatural elements. It has a lot about demons, angels, and other mythical creatures. The story also focuses on the protagonist's growth, both in power and in his relationships.
Power and its responsibilities is also a big theme. As the characters gain more power, they have to learn how to use it properly and not let it corrupt them. It's a constant struggle and a major part of their growth throughout the novel.
One of the main themes is growth. As I mentioned before, Issei's personal growth is central. He has to face various challenges and overcome his own weaknesses. Another theme is friendship and loyalty. The relationships between the characters, especially within Issei's peer group, show how they support and rely on each other through tough times.
One of the main themes is the supernatural world. It involves devils, angels, and other mythical beings. Another theme is the growth of the protagonist, Issei Hyoudou. He starts as a perverted high school student but gradually becomes stronger and more responsible.
One of the main themes is the supernatural elements. It involves devils, angels, and other mythical beings which create a complex and exciting world. Another theme could be the growth of the main character. He faces various challenges that force him to become stronger and more mature.
The main feature is its unique blend of genres. It has elements of action, with lots of battles between different supernatural beings like devils, angels, and fallen angels. For instance, Issei often has to fight to protect his friends and his new devil life. Another feature is the comedic aspect, especially with Issei's perverted nature providing many humorous situations.
Transformation is also a popular theme. Given ACNologia's nature, fanfictions may involve him undergoing some sort of transformation, either physically or in his personality. This can be due to the influence of the High School DxD environment or his interactions with the characters. And this transformation can then drive the plot forward in interesting ways.
Friendship is also a big theme. Characters from both universes form new friendships and alliances. For example, Naruto's idea of comradeship might influence the characters in High School DxD and vice versa. They learn from each other's values and work together to face challenges, whether it's school - related in the High School DxD setting or something more global like in Naruto's world.
One common theme is the exploration of relationships. Given the nature of the original series, many fanfictions focus on the romantic or friendship relationships between Uri and other characters.