A possible plot is that a powerful magical artifact in the wizarding world is actually a key to an ancient Stargate on Earth that has been long forgotten. Harry and his friends, along with the Stargate team, embark on a quest to find this Stargate. Along the way, they face challenges from dark wizards who also want the artifact for their own evil purposes and the Goa'uld who sense the power of the artifact. They must work together, using both magic and technology, to reach the Stargate and unlock its secrets.
The Stargate could be a portal between different magical realms in the Harry Potter universe. For example, it could lead to a place where ancient and more powerful magic exists. Wizards from different schools around the world could team up with Stargate explorers to uncover the secrets of this new place. There might be a new threat emerging from this realm that requires both magic and Stargate technology to defeat. This would bring together characters like Harry Potter and Jack O'Neill to lead the charge against the common enemy.
One idea could be that Voldemort discovers the power of the Stargate and tries to use it to gain more power. He could send his Death Eaters through the Stargate to conquer other worlds and bring back resources or powerful artifacts to help him in his quest to take over the wizarding world. The Order of the Phoenix would then have to follow through the Stargate to stop him.
The plot could involve Harry using his magic in the Stargate universe. Maybe he could use spells to help the Stargate teams in their battles against the Goa'uld. For example, a simple Stunning Spell could be very useful against the Jaffa warriors. He could also use magic to decipher some of the ancient technologies that the Stargate teams come across, since he has experience with ancient magic in his own world.
Perhaps in the crossover, the Prototype virus could somehow infect the magical creatures in the Harry Potter universe. This would lead to a crisis where normal spells and magic can't stop the infected creatures. Harry and his friends would have to seek help from Mercer, who understands the virus. Together, they could try to find a way to either cure the infected or contain the spread. Mercer might use his own knowledge of the virus and his powers to fight the infected creatures, while Harry uses his magic skills to protect Mercer from magical attacks.
One possible plot could be that the One Ring somehow finds its way into the wizarding world. Harry and his friends discover it and realize its dark power. Meanwhile, some Hobbits from Middle - earth are accidentally transported to Hogwarts. They team up with the Hogwarts students to keep the Ring away from the dark wizards who want to use it for evil, just like Sauron in their world.
Maybe there's a prophecy in both worlds that foretells of a combined force from the wizarding world and the ninja world being the only way to defeat an ultimate evil. So, Naruto and Harry are brought together. They face challenges in understanding each other's cultures and powers at first. But as they train together, they find ways to merge their skills. For instance, Naruto's rasengan could be enhanced with a magical spell to create a more powerful attack.
One main theme is the clash of cultures. The magical culture of Harry Potter and the technological culture of Stargate are very different, and seeing how they interact, like wizards being amazed by high - tech devices and Stargate personnel being astonished by magic, is a big part.
One idea could be that the Death Eaters in Harry Potter form an alliance with the Goa'uld from Stargate SG1. The combined forces of dark magic and alien technology would be a huge threat. The heroes would then have to combine their skills, with the wizards using spells to counter the Goa'uld's energy weapons and the SG1 team using their military tactics against the Death Eaters. Another idea is that the Hogwarts students go on a field trip through the Stargate. They encounter various alien races and have to use their magic to survive and make friends. This could be a great way to show how magic can be applied in a completely different setting.
One possible plot could be that Hogwarts students discover a Stargate on the school grounds. Maybe it was hidden by a powerful wizard in the past who had visited other planets through it. The students, led by Harry Potter, could then start to explore different planets through the Stargate. They might encounter alien races that have magical abilities similar to theirs, leading to a cultural exchange of magic and technology.
A possible plot is that Voldemort discovers the existence of the demigods and tries to use their powers for his own evil purposes. He sends his Death Eaters to capture some demigods. Percy and his friends manage to escape and seek refuge at Hogwarts. At Hogwarts, they learn about magic in a whole new way while also teaching the wizards and witches about their own powers. The two groups then have to combine their skills, like the demigods' combat abilities and the wizards' spell - casting, to fight against Voldemort and his new - found allies from the world of Greek mythology.