Maybe in the fanfiction, there's a magical artifact that forces Loki and Tony to experience different ages. They could start as old men, sharing their wisdom and regrets, and then gradually move to younger ages. At each stage, they discover new things about each other. For example, as teenagers, they might be more rebellious together and get into all sorts of trouble, which would be a far cry from their normal adult selves.
Well, an idea could be that Tony, in an experiment gone wrong, starts aging backwards rapidly. Loki, seeing this, decides to take care of him. Loki has to deal with a very young - minded Tony who is full of curiosity and mischief, much like Loki himself. This role - reversal of sorts, with Loki being the responsible one, can create some really interesting dynamics.
A fanfiction concept could be that Loki and Tony enter a virtual reality world created by Tony where age play is a theme. They can choose different ages and personas. Loki might choose to be a young prince again, and Tony could be a child prodigy. They interact in this virtual world, learning from each other's experiences at different ages and building a deeper connection that they then carry back to their real - life relationship.
There could be a fanfiction where Loki uses his magic to create an age - play - like dream for Tony. In this dream, Tony relives parts of his childhood, but with Loki present as a sort of guardian or companion. As Tony navigates through this dream world, he discovers new things about himself and his relationship with Loki. Meanwhile, Loki observes and learns more about Tony's past and how it has shaped the man he is today.
One idea could be that it's a magical or scientific accident that causes them to be in this situation. They might struggle with how society views their condition, especially in the superhero world where such a thing is unheard of. They could also have to deal with the physical and emotional changes that come with pregnancy, like mood swings and cravings.
One plot idea could be that they discover their 'brotherhood' through some magical or scientific accident. Maybe they have to team up to stop a common enemy, like an ancient, powerful being. They could start off hating each other because of their different personalities (Tony's brashness vs Loki's slyness), but as they face challenges together, they learn to respect and care for each other.
There are fanfictions where Loki uses his magic to help Tony with some of his tech experiments. In these stories, Loki is intrigued by Tony's intelligence and the advanced technology that he has created. Tony, on the other hand, is fascinated by Loki's magic and they exchange knowledge, leading to some amazing inventions and magical - tech hybrids.
One interesting story could be where Loki and Tony Stark are forced to team up against a common enemy from another dimension. They start off hating each other but gradually learn to respect one another's skills as they fight side by side.
One idea could be that Loki and Tony are both tributes in the Hunger Games. Loki uses his magic to create illusions and mislead other tributes, while Tony uses his tech - savvy mind to build improvised weapons from the resources in the arena. Their different skills and personalities would lead to some interesting interactions as they try to survive and maybe even outwit the Capitol.
One idea could be a crossover where Fenrir from the Harry Potter universe somehow gets transported to the realm of Loki. Loki, being the trickster, might see Fenrir as a tool for his own schemes. Harry Potter, perhaps in a quest to stop some dark magic related to Fenrir, ends up following him and has to deal with Loki's antics as well.
A fanfiction could also focus on Isabela and Hawke teaming up to help the people of Kirkwall during a difficult time, like a famine or a plague. They could use their different skills, Isabela's street smarts and Hawke's combat abilities, to gather resources and protect the vulnerable. This would show their altruistic sides and how they can work together for the greater good.
Another plot might involve the Avengers trying to figure out how to deal with de - aged Tony and Loki. They could be worried about Loki's intentions since he's usually a villain, but at the same time, they have to take care of a child - like Tony. This creates a lot of comical and tense situations.
One possible plot could be Loki initially trying to use Tony for his own gain but then truly falling for him. Maybe Loki, in his usual sly way, gets close to Tony to access some of Stark's technology, but as time passes, he discovers Tony's charm, intelligence and vulnerability, and his feelings turn sincere.