One common theme is Potter's leadership. In many fanfics, he uses his experiences to lead the students or the faculty in new directions. Another theme is friendship. Potter often forms new friendships or deepens old ones in these stories.
It's hard to say if there are popular 'professor potter pregnant fanfic' writers. Since fanfic is a niche area, and this is a very specific topic within that. There may be some writers who are known within the small community of readers interested in this type of fanfic, but it's not something that is widely known in the general fanfic or literary world. You would probably need to dig deep into the relevant fanfic communities to find out.
There's a fanfic called 'Professor Potter's Mysterious Assignment'. In this story, Potter is given a task that no one else can do. It delves deep into the magical lore and Potter's relationships with other faculty members. It's really engaging as it combines mystery and magic.
It's highly inappropriate. The relationship between Umbridge and Harry Potter is one of oppressor and oppressed in the original story. Adding such a violent and inappropriate act like spanking in a fanfic not only distorts the characters' relationship but also may have a negative impact on fans, especially younger fans who look up to the series for positive values and role models.
I'm not sure specifically which 'professor potter pregnant fanfic' stories are good. You could try searching on fanfic platforms like Archive of Our Own. They usually have a wide range of fan - created stories, and you can use the search function to look for stories related to this specific topic.
The novelty. Usually in the original series, we have a set idea of what professors are like. In a 'a different professor Harry Potter fanfic', they can be completely different in terms of personality. For example, a super shy professor who is an expert in Dark Arts but is always afraid to show off his knowledge.
A really cool fanfic idea could be that Professor Sinistra discovers Harry Potter has a natural aptitude for a very rare form of astronomy - based magic. She then decides to take him under her wing privately, away from the prying eyes of other professors and students. This could lead to a series of adventures where Harry learns this unique magic and uses it to solve problems at Hogwarts.
One popular 'a different professor Harry Potter fanfic' could be 'The Unconventional Professor at Hogwarts'. It might feature a professor with a unique teaching style or a different backstory that adds an interesting twist to the Hogwarts experience.
In Harry Potter fanfiction, a male professor can play various roles. For example, he could be a mentor figure like Dumbledore, guiding the young wizards. He might also be a villainous professor, creating obstacles for the main characters. Some fanfictions might explore a male professor's backstory, his relationship with other characters in the wizarding world, or his own magical research and discoveries.