Another idea is that Sherlock and Tony Stark team up. They are both highly intelligent. Tony could provide Sherlock with high - tech gadgets to aid in his investigations, while Sherlock could help Tony with his personal problems. For example, Sherlock might figure out who is trying to steal Stark Industries' secrets by observing the small details in the company's operations.
The Hulk could be a bit of a mystery to Sherlock. He would be intrigued by the dual nature of Bruce Banner and the Hulk. Sherlock might try to find a way to control the Hulk's transformations through his scientific knowledge and understanding of human psychology. Meanwhile, the Avengers would be both amused and impressed by Sherlock's unique methods.
Character development is also a big theme. Fans might write about how a character from one universe would change or grow if they were exposed to the other universe. For instance, how Tony Stark would interact with Sherlock and how that might influence his own character arc.
In the fanfiction, Sherlock could be investigating a series of disappearances that are somehow related to the Avengers. Maybe the disappearances are part of a plan by a new villain who wants to use the Avengers' powers for his own evil purposes. Sherlock would use his powers of observation to find clues that the Avengers missed. He could also get into some interesting debates with Captain America about justice and the law, as Sherlock has his own unique view on these matters. The story could end with them working together to rescue the captives and defeat the villain.
Sherlock would likely observe the Avengers closely. He'd be intrigued by their powers and abilities. For instance, he'd be very interested in the Hulk's transformation and how it affects Bruce Banner's psyche. He might try to find a way to control the transformation through his deductive reasoning.
Well, the Avengers are a diverse group. Hawkeye might just shrug it off as something he doesn't really care about. But Iron Man would likely be drawn to the technological aspects that might be added in some fanfictions. Captain America would be more interested in the moral and ethical elements that could be explored in the stories. Black Widow would be observant, noticing the different characterizations and how they deviate from the original Sherlock Holmes. And Thor would probably be the most out - of - place, trying to make sense of this strange new form of storytelling.
First, know both universes well. If it's a Sherlock and Harry Potter crossover, understand the rules of magic in HP and Sherlock's deductive methods. Then, create a unique plot. Maybe Sherlock is called to Hogwarts to solve a mystery that baffles the wizards. Also, keep the characters in - character. Sherlock should still be his brilliant, aloof self. And don't forget about good grammar and spelling.
One idea could be that Godzilla is drawn to the energy source of one of the Avengers' tech, like Stark's Arc Reactor. This causes chaos as Godzilla approaches the city where the Avengers are based. The Avengers initially see Godzilla as a threat and try to fight it. But then they realize that an even bigger alien force is using Godzilla's presence as a distraction. So, they have to find a way to communicate with Godzilla and work together to defeat the common enemy.
One idea could be that Nightwing is transported to the Avengers' universe through some sort of interdimensional rift. He then has to team up with the Avengers to fight a common enemy, like Thanos who has somehow acquired some of Batman's tech. Nightwing's acrobatic skills and detective abilities would be a great addition to the Avengers' power set.
Fanfiction.net is also a great place. There are many talented writers who contribute their works about the Avengers and Sherlock. You can search by tags or use the search bar to look for specific types of stories, like crossovers between the two universes or stories focused on a particular character from either.