Well, it's possible that such a fanfiction exists. However, this would be a very strange crossover considering that 'Dean and Sam' are from 'Supernatural' and 'Harry' is from the 'Harry Potter' series. It might be a very niche or even a dark and edgy take on combining these two universes. But again, without a proper search on the relevant fanfiction platforms, it's difficult to say for sure.
It would be really strange. Dean and Sam are used to dealing with demons and monsters in the Supernatural world. Harry Potter is a wizard in a different magical world. For them to kill Harry, there would have to be some sort of miscommunication or a really dark plot. Maybe some dark magic from the Harry Potter world is mistaken for demonic activity by Dean and Sam and they act on it wrongly.
No. Fanfiction involving sexual content between characters is often not appropriate as it violates the boundaries of the original work and can be disrespectful to the source material and its fans. Moreover, it may also make many people uncomfortable.
For Dean, you could develop his character as a vampire by emphasizing his protective instincts, but in a more vampiric way. He might protect his territory or his 'blood sources' aggressively. His giggling could come from a place of enjoying the power he has. For Sam, his intelligence could be enhanced as a vampire. He could use his smarts to find new ways to survive. His giggling might be more of a nervous reaction to the new and often immoral things they have to do as vampires.
One great fanfiction could be where Dean and Sam have to face a unique Halloween - themed monster. Maybe a witch who uses Halloween traditions to cast powerful spells. They would have to use their wits and hunting skills to stop her before she causes chaos in a small town.
A possible fanfiction plot could start with Dean being seriously hurt in a car accident on their way back from a hunt. Sam is distraught but quickly springs into action. He calls their hunter friends for help and takes Dean to the nearest safe house. There, he nurses Dean back to health. Sam is extra vigilant, setting up protective wards around the house and being overly cautious about any strangers approaching. He also spends time talking to Dean, helping him deal with the trauma of the accident both physically and mentally.
It could be that they love fanfiction that delves deep into their relationship. Stories that explore their brotherly bond more closely, perhaps with some emotional moments and how they support each other through tough times.
Another reason could be that fanfiction allows them to escape into a slightly different version of their world. It's like a form of relaxation for them. In fanfiction, they can experience things that haven't happened in their real lives yet, or see their relationships with other characters develop in new ways. Fanfiction gives them a chance to see themselves in different lights and situations, which can be both interesting and entertaining for them.
Sure. Sam and Dean often have moments that show their deep friendship. For example, when Dean was in danger, Sam would do anything to save him. They have supported each other through many tough times, like when they were facing powerful supernatural enemies. Their loyalty to each other is really remarkable.
A recurring theme is the search for their place in the world. As hunters, they don't really fit into normal society. Fanfictions explore how they deal with this outsider status. Another theme is the power of friendship. They have friends in the hunting community, and how those relationships interact with their brotherly bond is often a topic. Also, the theme of fate and free will comes up, as they seem to be following a certain path but also trying to break free from it sometimes.