One common theme is loyalty. The little brother is often portrayed as being extremely loyal to Sephiroth, no matter what. Another theme is discovery. The little brother might be on a journey to discover his own identity, which is often tied to his relationship with Sephiroth.
The theme of growth is quite common too. As the story unfolds, the little brother grows both in strength and character. This can be physical strength, like learning combat skills, or emotional strength, such as dealing with difficult situations or the complex relationship with Sephiroth. It makes the character more relatable and the story more engaging as we see his transformation over time.
Family and protection are also prevalent themes. Even in a fictional context, the idea of family is important. The little brother may be in need of protection from Sephiroth or vice versa. And sometimes, they both have to protect each other from external threats. For example, in some fanfictions, there are enemies that target them because of Sephiroth's status or the potential power of the little brother. This creates a lot of drama and action within the stories.
One common theme could be power. Both Harry and Sephiroth are associated with great power in their respective universes. So, fanfictions might explore how Harry's new - found connection to Sephiroth affects his power levels or how he uses it. Another theme could be identity. Harry having elements of Sephiroth in him might make him question who he really is.
Isolation is also quite prevalent. Vampires are often solitary creatures, and Sephiroth, being as complex as he is, is shown to be isolated even more so in these fanfictions. He may be shunned by others due to his vampiric state, or he may choose to isolate himself because of his new - found powers and the thirst that comes with being a vampire. And there's also the theme of the unknown. His vampiric abilities and how they work are often a mystery, and the fanfictions usually unfold this mystery gradually.
One common theme is redemption. Many fanfictions try to explore the possibility of Sephiroth finding redemption through his interactions with the original character. For example, the OC might show him a different way of life or values.
Protection is a very common theme. The big brother often takes on the role of protecting the little brother from harm, whether it's physical danger or emotional distress.
Themes of power and identity are quite common. Both Sephiroth and Cloud have strong identities related to their power. In fanfiction, it's often explored how their powers interact and affect their relationship. Additionally, the theme of destiny is often present. Whether they are fated to be enemies or if there's a chance for a different path for them.
One common theme is the exploration of her backstory. Since Sephiroth is such a complex character in the original, a female version might have a different backstory or the same one with a different emotional perspective. For example, how she dealt with her discovery of her origin.
A theme that's often explored is the blurring of good and evil. Cloud is typically seen as the hero and Sephiroth as the villain, but in fanfiction, these lines can get very muddy. Writers like to play with the idea that maybe there are more shades of gray to their characters, and this affects how they interact with each other.
In 'Harry Potter Sephiroth fanfiction', a recurring theme is the adaptation of Sephiroth to the new environment. He has to deal with the rules, cultures, and social structures of the wizarding world. There may also be a theme of power struggle, as Sephiroth's power could either be a threat or an asset in the fight against the dark forces in the Harry Potter series. Additionally, the theme of identity can be explored, as Sephiroth may question who he is in this new and different world.
Another theme could be the cultural differences between the two universes. The Final Fantasy world has its own set of values, and the Sekirei world has its own. Fanfiction might play with how characters from these different cultures interact and adapt. For example, Sephiroth might find the concept of Sekirei pairs very strange at first. It can lead to interesting character development and relationship building within the story. And this often makes for an engaging read as the author tries to blend these two very different worlds together in a believable way.
One common theme is redemption. After being hurt, Sephiroth often goes through a journey of redemption with the comfort he receives as a catalyst. Another theme is self - discovery. Through the process of being comforted, he starts to understand himself better.