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.
Another possibility is that the concept of death in both universes is related. In the Avengers universe, death is often averted or has major consequences. In the Harry Potter world, Harry has conquered death in a way. He could share his understanding of death and the afterlife with the Avengers. This might give them a new perspective on their battles and the sacrifices they make. For instance, if a major Avenger dies, Harry could use his knowledge to either bring them back or help them move on in a more positive way.
One way it could work is through the concept of alternate universes. In a Marvel - Potter crossover fanfic, the power of being the Master of Death could be seen as a sort of super - power. Harry could use his mastery over death to perhaps revive fallen heroes in the Marvel universe, like bringing back Bucky Barnes before his resurrection in the main storyline. This would create a whole new dynamic and set of relationships.
Well, in a RWBY fanfiction with Harry Potter as the Master of Death, one way it could work is through a cross - dimensional portal. Harry could be accidentally transported to the RWBY universe. His status as the Master of Death might give him unique powers there. Maybe he could use the Deathly Hallows' powers to combat the Grimm. For example, the Invisibility Cloak could help him in stealth missions against the Grimm, and the Elder Wand could enhance his combat abilities against powerful foes in RWBY.
A crossover could function through a portal or some sort of magical event that links the two worlds. For instance, the Tesseract in the Avengers universe could malfunction and open a portal to the Harry Potter world. Then, the Avengers find themselves in a world full of magic and wizards. They soon learn about the God of Death and realize that they need to work with the wizards like Harry, Hermione, and Ron to stop this ultimate force. The Avengers' powers would be a new and strange thing in the Harry Potter world, and the wizards' magic would be equally fascinating to the Avengers.
Well, in a fanfiction, one way it could work is if the concept of the Master of Death from Harry Potter was translated into the world of Soul Eater. Maybe the power of being the Master of Death could give the character an edge in dealing with the Kishin and the madness in Soul Eater. For example, the invincibility that might come with mastering death could help in battles against powerful foes.
One possibility could be that Harry uses his mastery over death to bring back some fallen Avengers. He might use his knowledge of powerful magic to enhance the Avengers' abilities. For example, he could place protective spells on them similar to the ones used in Hogwarts.
The characters' interactions could be really complex. Hermione would be eager to study the Avengers and their powers from a scientific and magical perspective. She might try to find parallels between magic spells and the Avengers' abilities. Captain America would respect the values of the wizarding world like loyalty and courage which are similar to his own. The Master of Death could play a role in bringing out the best in both groups. He could encourage Harry Potter to be more bold in his actions like the Avengers, and also teach the Avengers about the subtleties of magic. For instance, how a simple spell can have a profound impact on the world around them.
The fanfiction could show Harry using his skills as the Master of Death to resurrect certain key characters in the Avengers universe who have died. This would change the power dynamics and relationships within the team. He could also use his magic to teleport the Avengers to different locations quickly, which is something that could be very useful in their fight against powerful enemies. Also, his understanding of the Deathly Hallows could lead to some interesting plot twists where the Avengers have to help him protect these powerful artifacts from falling into the wrong hands.
The story could develop with Fem Harry Potter being a sort of wildcard in the Avengers. Her background in the wizarding world gives her a different perspective. She might initially struggle to adapt to the high - tech environment but then find ways to combine magic and technology. For instance, she could use a spell to enhance the power of Captain America's shield. And her experiences with dark magic could help the Avengers better understand and combat otherworldly threats that they haven't faced before.
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.
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.