A possible plot could be that a powerful dark wizard has captured Maximoff to use his powers for evil. Harry Potter, who is always fighting against the dark side, gets wind of this. He embarks on a journey to find Maximoff. Along the way, he has to face many challenges and obstacles. Once he reaches Maximoff, he has to use his quick thinking and powerful spells to defeat the dark wizard and save Maximoff. For example, he might use the Expecto Patronum spell to ward off Dementors or other dark creatures that the dark wizard has sent to stop him.
The plot could start with Harry Potter noticing strange magical anomalies. These anomalies turn out to be related to Maximoff's world. Harry decides to investigate and finds Maximoff in a dangerous situation. He then uses his magical abilities to rescue him.
The plot might involve a magical rift that has opened up between the Harry Potter universe and Maximoff's world. Harry, being curious and heroic, enters this rift. He discovers that Maximoff is being hunted by a group of rogue magical beings. Harry uses his knowledge of Hogwarts magic, such as Transfiguration to create distractions, and Potions to create defensive substances. He also uses his experience in dueling to take on these beings one by one. In the end, he saves Maximoff and in the process, learns something new about the vastness of magic and different magical worlds.
Well, perhaps there is a dark force that is after Maximoff and it's affecting different universes. Harry Potter, being the hero he is, senses this disturbance in the magical fabric. He travels to Maximoff's realm using his Patronus as a guide. Once there, he uses his knowledge of defensive magic, like the Shield Charm and Stunning Spells, to protect Maximoff and save him from the impending doom.
The plot could start with Harry somehow ending up in Gotham. He notices the Joker's chaos and decides to intervene. Harry might use his invisibility cloak to get close to the Joker without being detected at first. Then he could start using his magic to slowly disrupt the Joker's evil plans.
A possible plot could involve a new, powerful dark sorcerer who has found a way to combine magic from both universes to become invincible. Doctor Strange tries to stop him but is quickly overpowered. Meanwhile, Harry Potter senses the danger through his connection to magic. He travels to Doctor Strange's side. Harry uses his knowledge of magical creatures from the Forbidden Forest. He summons a group of Centaurs who help him in the battle. With their combined strength and Harry's strategic use of spells like the Stunning Spell, they are able to defeat the dark sorcerer and save Doctor Strange.
It could be really unique. Maybe Wanda's powers would be seen as a new kind of magic in the Harry Potter world. Harry could be fascinated by her abilities and they start to develop feelings. For example, Wanda could use her powers to help Harry in a battle against dark wizards in a way that no other Hogwarts student could.
One challenge would be the difference in their magical systems. Harry is used to the more rule - based magic of the wizarding world, like spells having specific incantations and wand movements. Wanda's magic is more instinctual and based on her emotions. This could lead to misunderstandings when they try to work together or teach each other their magic.
One major challenge would be the difference in their magical cultures. Harry is used to the wizarding society with its Houses, Hogwarts, and Ministry of Magic. Wanda comes from a world where she's often an outcast due to her powers. Another challenge could be the power imbalance. Wanda's powers are extremely powerful and could potentially overshadow Harry's. Also, they would have to deal with the different threats in their respective worlds. For example, Voldemort in Harry's world and various villains in Wanda's Marvel Universe.
Pietro's super speed could enhance Harry's ability to quickly move around Hogwarts during a battle or while searching for something. For instance, if Harry needs to reach the Room of Requirement in a hurry, Pietro can carry him there in an instant.
A possible plot could be that Tom Riddle is forced to save Harry Potter as part of a magical pact or curse. He initially resents it but as he spends time with Harry, he starts to see the world through Harry's eyes. For example, Harry's kindness towards others, even those who are different or outcasts, could make Riddle question his own beliefs. The fanfic could then focus on how Riddle tries to balance his old dark desires with his new - found respect for Harry and the values Harry represents. There could be a lot of internal conflict within Riddle as he tries to decide whether to fully embrace this new path or return to his old ways.
In one possible plot, Stark could be kidnapped by a powerful magical - technological hybrid villain. Fem Harry Potter, with her knowledge of both magic and her quick - thinking skills, tracks him down. She has to navigate through the unfamiliar high - tech world of the Marvel universe while also using her magic discreetly. Once she finds Stark, she uses a combination of spells and her own wits to defeat the villain and save him. This could also lead to an interesting friendship or partnership between them, with Harry teaching Stark a bit about magic and Stark introducing Harry to new technology.
If Harry Potter saves the Avengers in fanfiction, he would bring a whole new dimension to their battles. His knowledge of the magical world could be used to outwit enemies. He could create magical barriers to protect the Avengers' base or use the invisibility cloak to sneak up on foes. And his Patronus could be a great weapon against dark forces that the Avengers face. It would be a unique crossover where magic and superhero powers combine.