One creative interpretation could be that the Unbreakable Vow is used in a fanfic to bind two characters in a secret alliance against a new dark force. For example, two students from different houses might make the vow to protect a powerful magical artifact from being stolen by a group of dark wizards who are trying to use it to gain control over Hogwarts.
In the original series, the Unbreakable Vow is a very serious and rarely used magical bond. In fanfic, it can be more common. For instance, in fanfic authors might use it more often to drive the plot forward. They might have characters enter into the vow more casually (compared to the original where it was a big deal).
One common theme is identity. Harry has to figure out who he is as a vampire while still being Harry Potter. Another theme is loyalty. His vow often tests his loyalty to his friends and the wizarding world.
Well, there's often the theme of secrecy. In the wizarding world of Harry Potter, secrets are a big deal. When you add vampirism to the mix, Harry and Severus would need to keep that a secret even more. Also, the theme of redemption can be present. Maybe Severus is trying to redeem himself through his vow to Harry who has become a vampire. Or Harry is seeking redemption for some past actions in his new vampire - like state. And of course, the theme of forbidden love can also crop up in these fanfics, as the relationship between Harry and Severus is already complex and adding vampirism can make it even more so.
One great 'vampire harry vow fanfic' is 'The Vampire's Pledge'. It has an interesting plot where Harry discovers his vampire heritage and has to make a vow that changes his life. The story is full of action and mystery.
There are several places to look for such fanfics. Archive of Our Own (AO3) is a great resource. You can simply type in 'vampire harry severus vow' in the search bar and browse through the results. Some fanfics might explore the relationship between Harry and Severus in a world where vampires exist and there are special vows involved. Another option is Fanfiction.net, but AO3 generally has a wider range of fan-created content.
Well, just based on that title alone, it's difficult to determine its quality. There are so many aspects that make a Harry Potter fanfic great. For example, it could explore new relationships between the characters, or create exciting new magical adventures. But we don't know if 'skull is harry potter fanfic' does any of those things. So, it might be good, it might not.
I'm not sure if it's common. There are so many different types of fanfics in the Harry Potter fandom. Some focus on relationships, others on new adventures. While metamorph - related ideas are interesting, it might not be as common as, say, romance - centered fanfics.
Definitely not. The official Harry Potter series is aimed at a wide range of audiences, including children. The concept of 'harry potter panty fanfic' contains elements that are not suitable for the family - friendly and positive environment that the fandom has created around the series. It goes against the values of friendship, courage, and magic that are central to the Harry Potter world.
Definitely not. The Harry Potter world created by J.K. Rowling is meant to be a place of wonder, where readers can explore magic, good vs. evil, and strong friendships. 'Kinky' fanfic goes against this. It's not only against the family - friendly nature of the fandom but also disrespectful to the original work. Fans usually prefer fanfics that stay true to the essence of the books, with positive interpretations and new adventures that fit within the framework of the magical world.