A topic about Snape's teaching methods and how they impacted the students at Hogwarts could also be very engaging. It could show how some students might have actually learned a great deal from him despite his seemingly harsh exterior, and how his knowledge of potions and the Dark Arts influenced the students' understanding of magic.
One good topic could be Snape's role as a double agent and how Harry discovers the truth about him over time. This can involve a lot of mystery and intrigue as Harry tries to figure out Snape's true motives while Snape is constantly in a precarious position between the Death Eaters and Dumbledore. Another topic could be Snape mentoring Harry in potions in a more amicable way than in the original books, leading to a better understanding between them.
A good topic would be Hermione's role in reforming the wizarding world's educational system. Given her intelligence and love for learning, she could be depicted as leading initiatives to make magic education more inclusive and accessible to all witches and wizards, regardless of their background. This would show her as a strong advocate for positive change.
You could focus on the friendships between the characters. Maybe write about how the main characters form new alliances with other characters from different regions in the 'Kane Chronicles' universe. This could involve them working together to solve a mystery or face a new threat.
You could write about their adventures together. For example, how they explore a mysterious dungeon or face a powerful enemy side by side.
You could write about the 13th Doctor's adventures in new and unexplored galaxies. Maybe she discovers a new species and has to help them solve a complex problem. This would focus on her character as a hero and explorer.
You could write about his characters' adventures. For example, if he played in a fantasy world, you could write about his character's further quests, new friendships made, or battles fought. It would be exciting and stay within the realm of respect for the actor and his work.
Their shared secrets and the burden of them. They both had a lot of secrets, like Snape's true allegiance and Dumbledore's knowledge about certain things. A fanfiction could focus on how they dealt with keeping these secrets from others in the wizarding world.
A third theme could be Snape in alternate universes. For instance, a fanfiction could imagine what would have happened if Snape had joined the Order of the Phoenix earlier or if he had been sorted into a different house. This could explore how his character would have developed differently and how it would have affected the overall story of the wizarding world.
There are many great topics. For example, their post - Hogwarts adventures together, like exploring new magical lands or solving mysteries in the wizarding world. They could also be shown building a family, focusing on the joys and challenges of raising magical children.
One great topic could be his journey in the acting world. For example, you could write about his experiences on different movie sets, the challenges he faced while preparing for certain roles, and how he overcame them. This would give readers an inside look into his professional life.