One idea could be that the OC has to deal with the legacy of Black Widow. He might struggle with living up to her name while also trying to carve out his own identity in the superhero world.
You can start by giving him some of Black Widow's traits, like her combat skills and strategic mind. But also add his own unique qualities, for example, a different moral code or a special power.
First, give your OC a strong backstory. For example, if your OC was also trained in the Red Room, what made their experience different from Black Widow's? Maybe they had a mentor within the program who influenced them in a unique way.
One interesting Black Widow OC fanfiction could be about an OC who is a young protege trained by Black Widow. This OC might have unique skills and a backstory that intertwines with Black Widow's own past. For example, the OC could be from a similar program but with a different set of challenges.
The story might involve Naruto growing up in a world that's a mix of the Hidden Leaf Village and the Marvel universe. He could struggle with being different from the other ninjas because of his unique heritage. His relationship with his peers and teachers would be different as they try to understand his connection to Black Widow. And he might use her fighting techniques, like her acrobatic moves and use of various weapons, to become a more formidable ninja.
He might have enhanced physical abilities. Black Widow is known for her strength, agility, and combat skills. Naruto could inherit these, making him an even more powerful ninja in close - range combat. For example, his punches and kicks could be more forceful.
One possible storyline could be that their son inherits their skills. He might have Captain America's super strength and leadership qualities, combined with Black Widow's stealth and espionage skills. He could be on a mission to protect a powerful artifact from falling into the wrong hands, using his unique blend of abilities.
Well, he could also look more like Black Widow in terms of complexion. His skin might be a bit paler, and his features could be more delicate. But his overall presence would still be strong and heroic, with a sense of purpose that comes from both of his parents' legacies.
In fanfiction, the relationship between Black Widow and Hydra can be very complex. Some fanfics might explore her time within Hydra, perhaps delving into how she was indoctrinated or how she managed to resist their control. It could show her as a double agent from the start, using her skills to undermine Hydra's plans from the inside.
Hawkeye would be a great addition. Their friendship in the Marvel universe is well - known, and he could play a role as her confidant or partner in a mission. Another good character is Nick Fury. His connection to the spy world and his leadership could add depth to the story. Maybe he gives Black Widow a special assignment that delves into her past. Also, Maria Hill could be included. She and Black Widow could work together on a mission, and Hill's no - nonsense attitude could contrast with Black Widow's more complex and mysterious nature.