Another idea could be Harry learning magic from a time - traveling wizard from a far - off future. This would introduce futuristic magical concepts and technologies that he would have to adapt to. It could also lead to him having to use his traditional Hogwarts magic in new and unexpected ways to keep up with the advanced magic he's learning.
One idea could be that the Magic God decides to test Harry Potter by sending him on a special quest that involves both the wizarding world and the realm of the Magic God. Harry might have to use his unique skills as a wizard and also learn new powers bestowed by the Magic God.
Severus Snape is also a popular choice. His complex character and vast knowledge of magic can create interesting dynamics when he meets characters from different magical worlds. He could either be a mentor or an antagonist in these crossovers.
One interesting story could be Harry's initial struggles. He might face challenges like accidentally causing chaos as he tries to control his wandless magic. For example, he could make objects fly uncontrollably in the Gryffindor common room. Another aspect could be his secret training sessions. He might find a hidden place in Hogwarts, like an abandoned classroom, to practice without others knowing.
There are fanfictions where he learns elemental magic in a new way. For example, being able to combine fire and water magic in a unique and powerful way that was not explored in the original books. He could use this to create new defensive or offensive spells against dark wizards.
One great plot development could be that the elemental magic Harry learns is not part of the traditional Hogwarts curriculum. So, he has to seek out hidden mentors or ancient texts. This could lead to him exploring parts of the wizarding world that are long forgotten. As he delves deeper into elemental magic, he might also start to question the limitations of the magic he has been taught so far at Hogwarts.
There could be a book of ancient runes that holds the key to powerful spells. Another might be a tome about magical beasts, which gives Harry a better understanding of how to deal with them magically. And perhaps a book on forgotten magic arts that provides him with unique ways to use magic.
One of the interesting spells could be 'Tempestus Ignis' which creates a fiery storm in some fanfictions. It gives him a powerful offensive move against dark creatures.
Some concepts include crossovers with fairy tale worlds. Picture Harry Potter characters entering the world of Cinderella or Snow White. The magic in Harry Potter could transform the classic fairy tale settings. Another concept is a crossover with steampunk elements. In such fanfiction, you'd see magic integrated with steam - powered machinery and Victorian - era aesthetics. This could lead to the creation of new magical devices and a whole new look at how magic is used in a more industrialized setting. There could also be crossovers with alien races, where the wizards' magic is put to the test against extraterrestrial powers and technologies.
One interesting idea could be the creation of new and unique magic circuits that combine different spells or magical elements. For example, a circuit that mixes a protection spell with a levitation charm in a novel way. Another idea might be the use of magic circuits to enhance magical creatures' abilities, like creating a circuit for a hippogriff to fly faster. Also, some fanfictions might explore how magic circuits can be used to solve complex magical problems within Hogwarts, such as fixing the broken staircases more efficiently.
One interesting idea could be a new spell using lightning magic that only a chosen few can master. It might be a spell that can either protect Hogwarts in a more powerful way than existing spells or be used to track dark wizards by following the electrical impulses in their magic.