The 'found family' trope works well. The characters in 'Man to Man' often rely on each other like a family. A fanfiction that emphasizes this aspect, like when a new character is introduced and is slowly accepted into their 'family' unit. Also, the 'identity reveal' trope can be exciting. In the drama, there are already some secrets and identity reveals, but in fanfiction, you can create more complex and unexpected identity reveals that add more twists to the story.
One idea could be a prequel fanfiction. Explore the backstories of the main characters before they got involved in the events of the drama. For example, how did they train to become the agents they are? Another idea is a 'what if' scenario. What if the main character had made a different choice at a crucial moment in the drama? It could lead to a completely different storyline. Maybe a fanfiction where the characters go on a normal vacation together, away from all the action and danger, just to show their more relaxed and personal sides.
One common trope is the 'forbidden love' angle. Since it's an older man, it goes against the social norms in the wizarding world. Another trope is the 'mentor - mentee' relationship that often turns into something more. The older man might start as a guide to Hermione, like in magic studies, and then his feelings change.
Another trope could be that the white man OC is on a journey of self - discovery in the world of the hentai fanfiction. Maybe he has come to a new place and is exploring not only his sexual desires but also his understanding of relationships, all while being in a world filled with the unique elements of hentai such as exaggerated physical features and over - the - top scenarios.
The 'fish - out - of - water' trope can be great. Like when Spider - Man first arrives in Red Sonja's world. He's used to the modern cityscape of New York and now has to deal with a medieval - like environment full of swords, sorcery, and different social norms.
I'm not very familiar with this specific type of fanfiction, but in general, common tropes in gay fanfiction might include slow - burn romances where the characters gradually develop feelings for each other. Another could be the 'opposites attract' trope, given that He - Man and Beastman are quite different in nature. Also, there might be a trope of secret relationships, as their relationship might not be accepted in the context of their fictional world.
One popular trope is the 'enemies - to - lovers' between Rio and Beth. It adds a lot of tension and drama to the story. Another is Rio as the 'protector' in some way, even though he's a criminal. It gives an interesting twist to his character.
One of my favorite ideas is Iron Man time traveling to key moments in the history of the Marvel Universe. For instance, going back to the time when the Infinity Stones were first scattered across the cosmos. He could try to secure them or at least understand their power better, which would change the whole dynamic of the Infinity Saga in the fanfiction world. It would be a high - stakes adventure with lots of potential for different plot twists.
For Thor, it might be the action scenes where Iron Man is flying around and shooting things. He'd probably enjoy the display of power. Natasha might like the scenes where Tony is being clever and outsmarting his enemies with his technology.
One of the favorite scenes in Iron Man 3 Pepper and Tony fanfictions is when Tony shows Pepper his latest Iron Man suit upgrade. He's like a kid showing off his new toy, and Pepper's reaction can range from amused to impressed. It's a sweet moment that shows their closeness and how much Tony values Pepper's opinion.
The 'fish - out - of - water' trope is quite popular. Since Spider - Man is from New York and Wakanda is a very different place, seeing him struggle to understand Wakandan customs while Shuri finds his confusion both amusing and endearing. For example, when he first tries Wakandan food or attends a Wakandan ceremony.