One possibility in this fanfiction could be that the demons are bound by some ancient magic or prophecy to save Harry Potter. The wizarding world has always had its own magic and rules, and maybe there is a connection between the demons' world and the wizarding world that has been long forgotten. The demons find Harry in a moment of great peril, and despite their demonic nature, they are compelled to save him. They might face a lot of internal conflict within their own group as some demons might think it's against their nature to save a human, especially a powerful wizard like Harry.
In the 'Harry Potter Saved by Demons' fanfiction, perhaps the demons are not as evil as they seem in the traditional sense. They might be outcasts from their own demon realm. When they come across Harry, they recognize his power and the danger he's in. They decide to save him because they believe that by doing so, they can change the fate of both the wizarding world and their own world. So they use their unique demon abilities to keep Harry safe from harm.
It could be a group of lesser - known demons. For example, there might be a demon named Zargoth who has the ability to manipulate time and space a little bit. He could use this power to save Harry from dangerous situations. Another could be Lythra, a female demon with the power of illusion. She can create false images to deceive Harry's enemies.
The plot could be that Harry, raised by demons, has unique powers that other wizards don't. For example, he might be able to communicate with dark creatures more easily. The demons could be using Harry as a tool to infiltrate the wizarding world. When he gets to Hogwarts, he starts to question his upbringing as he sees the kindness and different ways of magic there. He has to decide whether to stay true to his demon - raised self or embrace a new way of life.
One possibility is that Harry Potter, in this fanfiction, might be exposed to a whole new set of dark magic and powers that demons possess. The demons could see his potential and decide to raise him in a way that is completely different from the wizarding world he knew. Maybe they would teach him to use his magic more aggressively or in ways that are considered unethical in the normal wizarding community.
Perhaps the story could show Harry being isolated from the wizarding world he was meant to be a part of. Since demons are raising him, they might keep him away from Hogwarts and the positive influences there. He could develop powers that are a mix of wizardry and demonic abilities, which would make him a very different kind of character in the fanfiction universe. He might also have a different view on good and evil, as demons' moral compass is not the same as that of humans or wizards.
Well, it could be a really wild plot. Maybe Harry discovers he has the ability to use his magic to make demons sing, and he uses this as a way to defeat Voldemort. For example, the demons' singing could have some kind of magical effect that paralyzes the dark forces.
Well, it might be that Harry Potter is accidentally transported to a non - magical realm where he is in trouble because he doesn't understand the Muggle world completely. The Queen, who has some knowledge of magic or is in contact with a secret magical society, discovers Harry and saves him from the perils of this strange new world for him.
One possibility could be that Voldemort has a sudden change of heart. Maybe he realizes that Harry is the only one who can truly understand his loneliness and power. So instead of killing Harry, he decides to save him from a dangerous situation, like a powerful dark magic that even Voldemort fears could destroy the wizarding world if not controlled, and in the process, they form an unlikely alliance.
Well, perhaps the Winchesters, who are known for hunting supernatural beings in their own universe, find a way into the Harry Potter world. Maybe they sense some dark magic that the wizards in Harry Potter's world can't handle on their own. They then use their skills and knowledge of the supernatural to save Harry from a powerful dark wizard or a dangerous magical creature.
Well, it could be that Hera, perhaps using her divine powers, steps in when Harry is in a really tough situation in the wizarding world. Maybe she saves him from a powerful dark spell or a dangerous creature. For example, when he's facing Voldemort, Hera could use her magic to shield Harry and give him the strength to fight back.
In such a fanfiction, perhaps Lockhart manages to overcome his usual self - centeredness. He could use his knowledge of various spells, which he often brags about but fails to execute properly in the original books. Maybe he finally remembers the correct incantation at a crucial moment to save Harry from a dark wizard or a dangerous magical creature. For example, if Harry is being attacked by a basilisk, Lockhart might remember the spell to stun it and save Harry just in time.