What could happen in 'Harry Potter summons a servant fanfic'?

It could be a house - elf. House - elves are known for their loyalty and their ability to do various tasks. They could be very useful to Harry, like helping him keep his dormitory clean or even spying on the Death Eaters.

Well, if Harry Potter summons Medusa in a fanfiction, it could be a total chaos. First, just the sight of Medusa could turn many around him into stone. His friends would be in immediate danger. Harry would have to find a way to either control Medusa or reverse the petrification effect. Maybe he'd use some advanced magic he learned from Dumbledore's old books. He might also try to communicate with Medusa, using Parseltongue perhaps, as he can talk to snakes. It would be a really wild and dangerous situation.

Well, first of all, the very act of summoning a demoness would likely be against the rules of Hogwarts. If Harry were to do this, he could face expulsion. Once summoned, the demoness could manipulate the minds of those around her, turning friends against each other. Harry would need to use all of his magical knowledge and courage to resist her influence and find a way to banish her back to where she came from. It could also attract the attention of dark forces outside of Hogwarts that might try to use the situation to their advantage.

The servant could do household chores. Just like how house - elves in the Harry Potter world usually take care of cleaning, cooking, and keeping the place tidy. For example, if Harry is living in Grimmauld Place, the servant could make sure the old and gloomy house is clean and habitable.

Well, it could be a really dark and twisted story. Maybe Harry accidentally summons Jack the Ripper while trying out a new and powerful spell. Jack the Ripper's presence in the wizarding world would cause chaos. He might start attacking wizards and witches, thinking they're just like his normal victims in the muggle world. The Ministry of Magic would have a hard time dealing with him as he's from a different era and has a very different and brutal modus operandi.

Perhaps Harry summons a celestial spirit during a moment of great danger. The spirit could be a source of great power, allowing Harry to defeat his enemies easily. For instance, if he was surrounded by Death Eaters, the celestial spirit could emit a blinding light that incapacitates them.

Another possibility is Winky. She is also a house - elf. Winky was a bit of a tragic character in the original books. In the fanfiction, if Harry were to summon a servant, her meek and somewhat lost nature might make for an interesting addition to Harry's side, and she could be summoned to help Harry with various tasks.

In a fanfiction, Harry could summon Sebastian to join a wizarding tournament. Sebastian is known for his combat skills. Harry believes that with Sebastian on his side, they can win the tournament and gain glory for Hogwarts. Along the way, they face many challenges from other powerful wizards and dangerous magical tasks.

Well, one possible plot could be that the servant Naruto summons is from a future time. This servant has knowledge of events that are yet to happen in the Naruto world. Naruto then has to use this knowledge wisely while also keeping the servant's origin a secret from others who might misuse it.

I'm not entirely sure if there is a specific 'Harry Potter summons the devil' fanfic. Fanfiction is a huge realm with all kinds of ideas. But in the official Harry Potter universe, magic is more about good - evil magic like summoning the devil is not in line with the main story. It could be a very niche and probably not very popular idea among the more traditional Harry Potter fans.