There could be a fanfic where a father and son are fans of both Harry Potter and Lord of the Rings. Maybe they have debates about which magic system is better, Hogwarts' magic or the magic in Middle - earth. They could also compare the heroic quests in both stories and how the main characters grow up in the face of danger.
A way to combine them in a father - son fanfic is to have the father and son be magically linked to both universes. Maybe they have a special ability that allows them to travel between the two. They could then introduce characters from one world to the other. For example, Gandalf could meet Dumbledore, and the father - son pair could be in the middle of this encounter, learning from both great wizards.
Many fanfiction writers are attracted to dragons in these universes because they are such iconic and powerful creatures. In the context of combining Harry Potter and Lord of the Rings, a dragon could be a bridge between the two worlds, maybe a dragon that was once in Middle - earth but somehow ended up in the wizarding world of Harry Potter, creating all sorts of interesting storylines.
One idea could be a crossover where the characters from Harry Potter are transported to Middle - earth. For example, Harry could meet Aragorn and they could exchange knowledge about magic and leadership. Harry's magic could be a new and strange power in Middle - earth, and Aragorn's warrior skills and wisdom could inspire Harry.
Dragons in these fanfictions can also represent power. In Harry Potter, a dragon might be a symbol of the raw, unbridled power that wizards have to control. In Lord of the Rings, a dragon's power could be related to the balance of good and evil in Middle - earth. If a dragon is awakened, it could tip the scales in the wrong direction, or if it's tamed, it could be a great asset to the good side.
One idea could be that Harry would use his magic skills to help the Fellowship in different ways. For example, he could use his Patronus to ward off the Nazgûl, as his Patronus is a powerful form of positive magic. Another possibility is that he would have an interesting interaction with Gandalf, two powerful wizards from different magical worlds coming together.
I really like 'The Dark Lord's Son: A New Path for Harry'. In this fanfic, Harry is raised by the Dark Lord's followers after Voldemort's victory. It shows a completely different Hogwarts, full of dark magic teachings. The story is full of twists and turns as Harry starts to question the world he's living in.
One great female Harry Potter Lord of the Rings fanfiction is 'The Magical Quest'. It combines the magic elements from Harry Potter and the epic adventure feel of Lord of the Rings. The story follows a female character who discovers she has the powers of both worlds and has to go on a journey to save both magical realms. It's really exciting and full of unexpected twists.
One common theme is the power of friendship. In both original works, friendship plays a huge role, and in fanfiction, it's often explored further. For example, in crossovers, characters from both universes form new friendships based on shared values.
There might be a fanfiction where the characters from both universes meet. Picture Harry Potter and his friends meeting Aragorn and the Fellowship. They could exchange knowledge about magic and combat, leading to a unique and exciting adventure. This type of crossover fanfiction often explores how different magical systems interact.