Another idea is that a magical artifact in the Harry Potter universe gets into the hands of a demon in Dean's world. Dean and Harry have to work together to retrieve it. Along the way, they face challenges like dealing with Hogwarts' magical defenses and Dean's usual array of supernatural foes. Dean might be shocked by things like thestrals and the magic of the Marauder's Map, while Harry would be intrigued by Dean's Impala and his collection of weapons.
Perhaps there is a prophecy in the wizarding world that involves a hunter from another realm, which is Dean. Harry Potter is tasked with finding him. When they meet, they initially clash due to their different ways of doing things. Harry is used to following the rules of Hogwarts and the wizarding world, while Dean is more of a maverick hunter. But as they face a common enemy, like a powerful dark entity that wants to destroy both the wizarding world and Dean's world, they learn to combine their skills and defeat the foe.
One plot idea could be that Dean Winchester somehow gets transported into the wizarding world. He might team up with Harry Potter to hunt down a dark wizard who is using dark magic to summon demons. Dean's knowledge of the supernatural from his own world would be a great asset, and Harry could introduce him to the magic of spells and potions.
One idea could be that Dean and Elena meet when Dean is on a hunt in Mystic Falls. They initially clash because of their different approaches to dealing with the supernatural, but then they realize they can learn a lot from each other. Another plot could involve them teaming up to fight a common enemy that is a threat to both the world of Supernatural and The Vampire Diaries. For example, a powerful demon - vampire hybrid.
One idea could be a crossover where the magical world of Severus Snape and the hunting world of Dean Winchester collide. For example, Dean could end up in Hogwarts and Severus has to deal with this strange, non - magical yet very capable hunter in his midst.
The unique crossovers that can occur. In these fanfictions, we can see elements from both universes blend. Maybe there are spells being used to fight demons or the Impala (Dean's car) being enchanted by Harry. These crossovers create a whole new set of scenarios that are both familiar to fans of both series and yet completely new and exciting.
One idea could be that Harry Potter stumbles upon Newt's suitcase in the Forbidden Forest. He gets pulled into the magical world inside the suitcase and has to help Newt with a new, dangerous magical creature that has escaped. It would be exciting to see Harry use his skills from fighting Voldemort in this different kind of magical adventure.
Perhaps a plot where Dean is pregnant and barefoot in a post - apocalyptic world. He has to survive not only for himself but also for the baby. His skills as a hunter are put to the test in a different way as he has to find food and shelter suitable for his condition. He might also face challenges from other survivors who either want to harm him or take advantage of his situation.
Another interesting type of fanfiction could be a story set in an alternate universe where Harry Potter grows up in a world similar to Dean Winchester's. So, instead of Hogwarts, he's trained in hunting monsters like Dean. This would completely change his character development and the way he uses his magic powers in a more combat - oriented way.
One plot idea could be that Dean, as a girl, has to deal with the different ways people treat her in the hunting world. Maybe some monsters underestimate her at first, but she quickly shows them she's still as tough as ever. Another idea is that she has to navigate her relationships with Sam and Castiel in a new way, especially any potential romantic feelings that might change or emerge because of her new form.
One possible plotline could be that they meet in a strange supernatural - yet also a bit mundane - situation. Maybe Dean Forester, being from a more normal world, is initially very confused by Dean Winchester's world of hunting monsters. They could start off as adversaries, with Forester thinking Winchester is a bit crazy for believing in ghosts and demons. But as the story progresses, they could learn from each other. Forester could teach Winchester about the simple joys of normal life, like having a stable job and a regular home, while Winchester could show Forester how to be brave in the face of real danger.
Another theme is friendship. Fanfictions might show how Dean forms new friendships in the Harry Potter world, like with Hermione and Ron, and how his friendship with Harry is based on their shared experiences of facing danger. It's about different characters coming together and relying on each other, despite their different origins.
One popular story could be 'The Unlikely Bond'. It explores the unique situation where the two characters from different universes are brought together in this rather strange mpreg concept. It has a lot of character development as they both struggle to adapt to the situation.