Often, there is the theme of self - discovery through pain. Issei might face difficult situations that force him to re - evaluate himself and his relationships. Also, themes of redemption can be present, where Issei tries to make up for his mistakes while dealing with the hurt.
One common theme could be emotional pain. Issei might be going through heartbreak, betrayal, or loss in the fanfiction. Another theme could be physical harm, perhaps from a battle or an accident.
The theme of isolation is also quite common. When Issei is hurt, he may be pushed away from his friends or allies, and the fanfiction could explore how he copes with being alone. Additionally, the struggle to overcome the hurt and regain his strength and confidence can be a central theme in many 'issei hurt fanfiction'.
A common theme is power. How Issei gains power from Amaterasu or how they combine their powers. For example, in many fanfictions, Issei's combat abilities are enhanced by Amaterasu's divine energy.
Many fanfictions focus on Issei's role within the devil society. How he rises in rank, earns respect, and changes the way things are done. There are also themes related to loyalty and friendship. His relationships with his friends and comrades are often explored, showing how they support each other in the face of various challenges in the dangerous world of 'High School DxD'.
One common theme is power - up. Issei often gains new powers or abilities in these fanfictions. Another theme is romance, usually involving his relationships with different female characters in the series.
Well, the theme of sacrifice is quite prevalent. Sometimes either Issei or Rias has to sacrifice something for the other or for the greater good. Another common theme is identity. Issei, as a human - turned - supernatural being, and Rias, as a devil, both struggle with their identities at times. Their relationship helps them to better understand themselves. And the theme of destiny often comes up, as if they are fated to be together and face all these challenges as a couple.
One common theme is the growth of their relationship. It often starts from a somewhat distant or one - sided view and develops into a deep and meaningful connection. Another theme is their combined strength in battles. Writers like to show how they complement each other in fighting against enemies.
A significant theme is also self - discovery. Being reborn gives Issei a chance to look at himself and his role in the world differently. He might question his previous actions and strive to be a better version of himself. Additionally, alternate universe scenarios are common. The fanfictions may take Issei to different settings or situations that deviate from the original plot, like a world where the power balance is completely different or where certain events didn't occur as in the original story.
Romance can also be a theme. In some issei crossover fanfictions, he might develop relationships with characters from the crossed - over world. For instance, in a crossover with a magical girl anime world, he could end up having a romantic interest in one of the magical girl characters, which then adds an extra layer of story - telling as he tries to balance his feelings with his mission or place in the new world.
One common theme is friendship development. They often start as acquaintances or even rivals and gradually become good friends. For example, in many fanfictions, they work together on a project and through that, their bond deepens.
Well, a prevalent theme might be power. As a vampire in the fanfiction, Issei could be on a journey to discover and control his newfound vampiric powers. This might involve training, making mistakes, and learning from them. Also, the theme of love and relationships could be present. He may fall in love with someone who is either human or another supernatural being, which would bring its own set of challenges.
Love and friendship are often explored as well. It could start as a friendship that gradually develops into something more. Or perhaps they are forced to work together due to some external threat and in the process, they develop deep feelings for each other. The stories might also touch on themes of loyalty and sacrifice as their relationship progresses.