In this fanfiction, it could be that Hela is in need of something that only Harry can provide. Maybe a magical item from his world that has the power to heal a wound she got in a previous fight. Their meeting then becomes a journey of discovery and cooperation as Harry tries to find the item and Hela protects him during the search.
One idea could be that Hela somehow ends up in the wizarding world. She might be intrigued by the magic there which is different from her own powers. Maybe she tries to take over Hogwarts, thinking it's a place of great power. Another could be that Harry Potter has to team up with Hela to defeat a common enemy that threatens both the wizarding world and Asgard.
One idea could be that Harry discovers his true mother is Hela and has to deal with the new identity. He might face discrimination from some in the wizarding world who fear Hela's reputation. Another could be that he inherits some of Hela's powers, like the ability to control the dead in a more magical way than normal necromancy in the Harry Potter universe.
One idea could be that Hela, being a powerful Asgardian, somehow gets transported to the Naruto universe. She could initially see the ninja as weaklings but then be impressed by their unique chakra abilities. For example, she might be intrigued by Naruto's Nine - Tails chakra and see it as a power source similar to her own in a way. Another plot could involve Naruto having to team up with Hela to fight a common enemy that threatens both their worlds, like an ancient evil that can cross dimensions.
One idea could be that the actors from the Harry Potter movies get magically transported into the wizarding world of Harry Potter. They could use their knowledge of the story to help the characters, or they could be completely bewildered and cause chaos. For example, Daniel Radcliffe could end up having to explain to Harry Potter himself how his story is told in the Muggle world.
One idea could be that Harry Potter and his friends accidentally get transported to the RWBY world. They could then use their magic in unique ways to help the RWBY characters fight Grimm. For example, Hermione could use her knowledge of spells to create new defenses against the Grimm that the RWBY characters haven't thought of before.
One idea could be that Hela, as the self - inserted character, tries to reform the Avengers from within. She could use her unique powers and knowledge of Asgardian lore to help them face a new, powerful enemy. Maybe she starts off as a suspicious figure but gradually gains their trust through her heroic deeds.
Well, in a Loki meets Hela fanfiction, it might start with Loki being forced to meet Hela in Helheim. He could be there on a mission for Thor or Odin. Hela might be intrigued by Loki's presence. She could offer him a deal - his freedom in exchange for helping her gain access to Asgard again. Loki would have to weigh the options and decide if he can trust Hela or if he's just walking into another one of her traps.
One idea could be that Harry discovers Narcissa has a secret mission to undermine Voldemort from within. Maybe she's been secretly helping the Order of the Phoenix all along and Harry stumbles upon this knowledge.
In a 'Harry Potter meets Tom Riddle' fanfiction, a really unique plot could be that Tom Riddle is reborn as a normal wizard without the dark desires due to some powerful magic. Harry Potter meets this new Tom and they become friends at Hogwarts. However, there are still some remnants of the old Tom's power that attract dark forces. So, Harry and Tom have to work together to fend off these threats while also exploring Tom's new identity and how it affects the future of the wizarding world. This would involve a lot of character development for both Harry and Tom, as they navigate their relationship in this new scenario.
A plot could revolve around a magical artifact that has been stolen from Hogwarts. Harry and Pansy are the prime suspects in each other's eyes. But as they start to investigate, they realize they are being framed. They then team up to find the real thief. Along the way, they discover that they have more in common than they thought, like their love for Hogwarts in their own ways. As they search through the dark corners of the castle and the Forbidden Forest, their relationship evolves from animosity to respect.