Sure. In a typical 'Harry Blood Adopts Hermione' fanfic, the story often begins with Hermione in a difficult situation. Maybe she's an orphan or in a bad home environment. Harry, for some reason, decides to adopt her. Then, they start to build a new life together. Harry uses his knowledge and experiences in the wizarding world to protect and guide Hermione.
A great fanfic in this category is 'Adoption's Magic'. It not only focuses on the adoption aspect but also on how Hermione becomes an important part of Harry's family. The story has a lot of heartwarming moments as Hermione adjusts to her new family and how she in turn helps Harry deal with his own family - related issues.
In such a fanfic, it would be a very strange and dark twist. Voldemort might use Harry and Hermione to gain more power in a different way. Maybe he wants to corrupt them and turn them against Dumbledore and the Order. He could also try to use their knowledge, especially Hermione's vast magical knowledge, for his own evil plans.
A possible plotline is that Snape's adoption of Harry causes a rift in the wizarding community. Some might support it, seeing it as a way to keep Harry safe and under the watchful eye of a powerful wizard. Others might oppose it, fearing that Snape's dark past could influence Harry negatively. This conflict could lead to many adventures and challenges for both Snape and Harry as they try to navigate through the political and social turmoil.
Harry would probably become more conflicted. His views on good and evil would be severely tested. Hermione might become more cunning as she tries to outwit Voldemort while living under his roof. Voldemort himself might develop a strange sort of attachment to them, which could make his actions even more unpredictable.
He could develop more patience. Harry, being a curious and sometimes headstrong boy, would test Snape's limits. But as he grows into the role of a father figure, Snape learns to be more patient and understanding, which is a big change from his usually short - tempered self in the original series.
I also recommend 'Adopted by Harry'. This fanfiction focuses on the impact of Hermione's new family situation on her Hogwarts life. It's quite heartwarming to see how Harry tries to give Hermione the family she never had and how she blossoms in this new environment.
One common theme is family. Since Sirius is adopting Harry, it focuses on building a new family structure for Harry, different from the one he had with the Dursleys. Another theme is protection. Sirius is always on guard to protect Harry from the threats that still lurk in the wizarding world.
One key element is their relationship. In a fanfic, it can be explored more deeply, like how they support each other during the difficult times of the Half - Blood Prince's year. For example, Hermione might be more protective of Harry as he gets drawn into the mystery of the potions book.
There's a fanfic where Harry and Hermione in the Half - Blood Prince time start to investigate the true identity of the Half - Blood Prince more closely. They might face some challenges that test their friendship and intelligence. It often has them using their unique skills to piece together clues from the potions book and other sources around Hogwarts.