In Norse mythology, Hel is a figure associated with the underworld. In this fanfiction, she could be a character who has some sort of connection to the wizarding world. Maybe she's a powerful witch from a different magical realm that Harry encounters and eventually marries.
A possible fanfiction could be about a character from Naruto being summoned to the world of Smite by Hel. She could have an ulterior motive, like using Naruto's chakra for her own dark purposes. Naruto, not understanding the new world at first, has to quickly adapt and use his skills to either escape Hel's clutches or find a way to work with her to solve a greater problem that affects both his world and the Smite world.
To write a good fanfiction, do a lot of research on the Naruto universe and the Smite game. For the Naruto part, study the different jutsus, the relationships between characters, and the overall theme of friendship and growth. In Smite, understand the mechanics, the gods, and how Hel fits into the game world. Then, start with a strong hook, like Naruto suddenly appearing in the Smite world and being confronted by Hel. Develop the story from there, making sure to keep the characters' personalities true to their original sources.
In a 'Harry Potter raised by Hel' fanfiction, Harry could have a very different social structure around him. Hel might surround him with beings from Norse mythology. He would learn different forms of magic, like rune magic perhaps. His relationship with Dumbledore would be non - existent or very different. He might not even attend Hogwarts. Instead, he could be trained in a place that combines the elements of the Norse underworld and magic. His character would likely be more brooding and less inclined to trust the 'light' side of the wizarding world as he was not influenced by the positive Hogwarts environment.
Well, perhaps in this fanfiction, the reason for Harry being married to Hel is a magical prophecy. Their marriage could be a key to solving some greater threat. For example, Hel might have powers that are crucial in defeating a new dark force. And as they get married, they have to learn about each other's worlds and cultures, which would be a great source of conflict and growth.
Often, there are themes of adventure. The oc and the Hel Avenger might go on quests or face challenges together. Another theme could be self - discovery. The oc might discover new aspects of themselves through their interaction with the Hel Avenger. And there could also be themes of friendship or even romance developing between the two characters in the fanfic.
I recommend two books,"No Agreement Under Slaughter" and "Relieve Resentment--Plan Before Acting." The former told the story of the reincarnation of a King of Hell, while the latter told the story of a woman who had been exiled to the Netherworld Realm to take revenge. It involved the elements of King of Hell and the Netherworld. I hope you like this fairy's recommendation. Muah ~😗
He'd likely be more attuned to the darker aspects of magic. Since the Hel Gods are associated with darker realms, Harry might not shy away from what's considered 'dark magic' as much as in the original story. He could be more of an outcast among the regular wizards who fear his different upbringing.
He'd be more reserved. Hel's influence would make him less likely to trust easily. He wouldn't have the same sunny disposition as he might have had if raised by the Dursleys and then influenced by Hogwarts. He'd be more attuned to the darker aspects of magic and life in general.
Well, you can try searching on some popular fanfic platforms like Archive of Our Own. There are often a lot of such stories there. Just use the search term 'oc x hel avenger' and you might find some really interesting ones that suit your taste.