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.
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.
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.
Well, one possibility could be that Arcturus Black uses his powerful magic skills to rescue Harry from a dangerous situation. Maybe Harry is trapped in a dark wizard's lair, and Arcturus arrives just in time to fend off the bad guys with his advanced spells.
Perhaps Voldemort has cast a powerful spell on Harry that the normal wizarding community can't break. But the house elves, with their different kind of magic, are not affected in the same way. They detect Harry's plight and use their loyalty and cleverness. For example, they might create a magical shield around Harry that slowly weakens the dark spell, eventually saving him.
One possible plot could be that L, with his extraordinary detective skills, discovers a plot against Harry Potter early on. He might use his intelligence network to find out about Voldemort's plans and then intervenes at a crucial moment. For example, when Harry is about to be attacked by Death Eaters, L shows up and uses his strategic mind to outwit them and save Harry.
Well, perhaps Remus arrives just in time to save Harry from a group of Death Eaters. He uses his werewolf skills and magic to fend them off.
I'm not sure specifically as there can be many different interpretations in fanfiction. But generally, it might involve Harry Potter being in a dangerous situation and the goblins coming to his rescue. Maybe he's facing a powerful dark wizard and the goblins use their unique skills or magic to save him.