Well, perhaps the lawyer character could be a Muggle - born in the Harry Potter world who is a huge Avengers fan. They somehow end up in a situation where they have to use their lawyering skills to represent the Avengers against some sort of magical - technological threat that combines elements from both universes. They might argue about who has the right to certain magical artifacts that are now in the hands of tech - savvy villains.
It could work if the characters from both universes were to cross over. Imagine Harry Potter and his friends joining the Mobile Infantry. Harry's leadership skills and his ability to think on his feet, which he developed while fighting against Voldemort, could be very useful in the battles against the bugs. Hermione's vast knowledge of magic could be applied to find new ways to combat the alien threat. Ron's loyalty and courage would also be valuable assets. The different cultures of the two universes would also create interesting clashes and collaborations.
One way it could work is by having a magical portal open between the Harry Potter universe and Shao Kahn's realm. Harry and his friends could be accidentally transported there. Then they'd have to use their magic to survive in a world full of Outworld's warriors. Maybe they'd teach some of the magic to the good - hearted people in Outworld and in return learn some of their combat skills.
Well, if we consider the crossover in a fanfiction, Tate could be a dark force in the Harry Potter universe. He could be influenced by Voldemort's ideology. However, his own complex personality might make him a more nuanced villain compared to the typical Death Eaters. He might have his own motives for causing chaos in the wizarding world.
The main character could be Hermione Granger. Since she is very intelligent and has a strong sense of justice, she could easily be re - imagined as a lawyer. She could use her vast knowledge of magic and her quick thinking to bridge the gap between the two worlds and help the Avengers out. For example, if there was a spell that was being misused in the Avengers' world, she could figure out how to stop it legally.
The concept could work by having Harry bring the magic of the wizarding world into the Avengers' realm. His knowledge of potions could be used to create elixirs that give the Avengers new abilities. He could also use his wand to control the elements, like Thor does with his hammer, but in a more magical way. This would make him a valuable and almost god - like addition to the team.
Perhaps in a fanfiction, Voldemort has made an alliance with a powerful villain from the Avengers' world and an ancient order of Assassins gone bad. Harry Potter, along with some of his Hogwarts friends, has to convince the Avengers to help them. They would then combine their different abilities. For example, Hermione could use her vast knowledge to figure out the weaknesses of their enemies, while Captain America could lead the group in battle strategy, and the Assassin could provide crucial intel on the secret workings of the enemy alliance.
One idea could be a crossover where Hydra discovers the wizarding world in the Harry Potter universe and tries to use magic for their evil purposes. The Avengers somehow get wind of this and team up with Harry Potter and his friends to stop Hydra. Maybe they have to battle magical creatures that Hydra has corrupted with dark magic.
Well, it could be a time - travel fanfic. Harry Potter and his friends travel back in time and meet Queen Elizabeth. They could help her deal with some threats to the throne using magic, and in return, she offers them something valuable in the wizarding world, like a special magical artifact that has been lost in the Muggle world for centuries.
It could be a wild and exciting mix. Imagine Harry Potter and his friends suddenly in the Marvel universe during Infinity War. Harry could use his magic against Thanos. Maybe Hermione would figure out a way to counter the Infinity Stones' power with her vast knowledge. Wizards and superheroes teaming up would make for some really cool battle scenes and unexpected alliances.
It could work if the Infinity Stones and the Deathly Hallows had some sort of connection. Since Harry is the Master of Death, he might be sensitive to the power of the Stones. The Avengers are dealing with the Stones' power, and Harry could bring his knowledge of dealing with powerful magical artifacts from his world. He could teach the Avengers about the consequences of misusing powerful items and how to safeguard against the corrupting influence of such power.