One idea could be that Billy and Steve's kids inherit their dads' competitive streaks. They might compete in a school sports event, which leads to some sibling rivalry but also shows how they support each other in the end. Another could be that the kids discover a hidden talent for music, just like how their dads had hidden depths. For example, they form a band and perform at a local event.
The relationship between Billy and Steve is full of contrasts. Billy is often more hot - headed while Steve is more level - headed. Their kids could show this in how they handle emotions. One kid might be quick to anger like Billy, but the other could be the calm one, like Steve, and they balance each other out. They might also show their dads' relationship in their love for each other. Just as Billy and Steve support each other, the kids are always there for one another, through thick and thin, whether it's helping with homework or dealing with a personal crisis.
Perhaps in a post - Endgame world, Tony didn't die but lost his memory. Steve takes it upon himself to help Tony regain his memories. Along the way, they re - explore their relationship, the Avengers, and all the events that led to that point. Steve shows Tony videos and tells stories, and slowly Tony starts to remember, leading to a renewal of their friendship and a new start for the Avengers.
Perhaps in the fanfiction, they decide to start a family right away. But there are complications. Kono has some concerns about her ability to balance being a mother and still being part of Five - 0. Steve is very supportive, and they go through a journey of trying to make it all work. There could be some drama with their friends and colleagues as they adjust to the idea of Kono and Steve becoming parents.
A possible plot for Billy and Mandy crossover fanfiction is that they end up in a world of magic school. Billy is completely clueless about magic at first and keeps causing chaos in the classes. Mandy, on the other hand, is intrigued by the different types of magic and tries to learn as much as she can. They get involved in a competition between different houses in the school, and their friendship is tested as they face various challenges and temptations during the competition.
One idea could be that they discover they are going to be parents unexpectedly and have to deal with the reactions of their friends and family. It could be a comical situation as they are both rather unconventional characters. For example, Grim might be shocked and initially try to find a way to reverse it, but then slowly warm up to the idea of being an 'uncle' of sorts.
One plot idea could be that Natasha and Steve are on the run from some new threat while Natasha is pregnant. They have to constantly find safe places to hide and also deal with the physical and emotional challenges of the pregnancy. Steve is overly protective and Natasha is trying to be as tough as ever, which leads to some cute and tense moments between them.
Maybe Bucky kidnaps Steve because he believes it's the only way to protect him. There could be a new and powerful threat that Bucky has discovered, and he thinks that by taking Steve away from the public eye and the Avengers, he can keep Steve safe. But Steve doesn't understand Bucky's motives at first and there's a lot of tension between them until Bucky can explain.
Perhaps Steve gets hurt during an underwater mission. He could be attacked by some sort of sea creature or caught in a dangerous underwater current. His team would then have to deal with his absence and also figure out how to complete the mission without him. Meanwhile, Steve is in the hospital, frustrated at not being able to help, and has to rely on his mental strength to stay positive during his recovery.
One plot idea could be that the OC is a scientist who is working on a top - secret project related to time travel, and Steve gets involved. They have to work together to prevent a villain from changing history. Along the way, they develop a deep connection as they face challenges and discover each other's true selves.
One idea could be a time - travel plot where Darcy accidentally gets sent back in time and meets a young Steve and Bucky. They end up on an adventure together, with Darcy's modern knowledge helping them in unexpected ways.