One possible plotline could be that Harry Potter discovers a portal to the Marvel universe and meets Stephen Strange. Strange then takes Harry under his wing to teach him the mystic arts, which Harry uses to enhance his own magic when he returns to Hogwarts. Another could be that a threat in the wizarding world is so powerful that the Ministry of Magic seeks help from Stephen Strange, and he comes to Hogwarts to help fight the dark forces using his unique abilities.
Friendship or a deeper relationship is also a common theme. Many stories show them starting as strangers or even rivals and then evolving into friends or something more. They learn to respect each other's abilities and personalities. For example, Stark might initially be skeptical of Strange's magic, but as they work together, he comes to admire it. And vice versa, Strange might be put off by Stark's arrogance at first but then sees his good heart. It's about two very different people finding common ground.
One of the best fanfiction moments could be when Stephen Strange uses his magic to save Tony Stark during a particularly dangerous battle. Maybe Stark's suit malfunctions and he's about to be hit by a powerful energy blast, but Strange conjures a shield of magic just in time. This shows the synergy between their powers.
Well, perhaps the plot could involve Stephen Strange using his magic knowledge to train Harry in different forms of magic that are more advanced than what he learned at Hogwarts. Maybe he teaches Harry about dimensional magic, which could be used to access new places or even different timelines in the wizarding world.
One interesting story could be where Harry Potter, with his magic from the wizarding world, teams up with Stephen Strange in the multiverse. Maybe they combine their powers to fight a common magical threat that spans across different dimensions. For example, a dark entity that is causing chaos in both the Marvel universe and the wizarding world.
Some smaller, more specialized fanfiction communities or forums might also have such stories. For example, certain sub -reddits dedicated to fanfiction or crossovers could be a good place to look. However, these might require more digging and participation in the community to find the exact stories you're looking for.
One popular trope is the 'enemies to lovers' trope. Given their different personalities and initial interactions in the MCU, it's interesting to see how they might overcome their differences and fall in love in fanfic. Another is the 'hurt/comfort' trope. Maybe Tony gets injured during a battle and Stephen has to use his magic to heal him, leading to a deeper connection.
There's 'The Stark - Strange Alliance'. In this fanfic, they start off as reluctant allies but gradually develop a deep bond. It shows how their unique skills complement each other. For example, Stark's technological genius and Strange's magic. It's a really engaging read that plays with the idea of what could happen when these two powerful characters work together closely.