One common theme is the discovery of hidden powers. Since Harry is Merlin's heir, he often uncovers abilities that were previously unknown to him, like advanced spell - casting or magic related to nature.
Power and responsibility is a big one. Since the character has a connection to Merlin, they have to deal with the power that comes with it and the responsibility to use it well. Also, the exploration of ancient magic and how it fits into the existing Harry Potter magic world is quite common. For instance, they might explore how Merlin's magic is different from what is currently taught at Hogwarts. There could also be themes related to prophecy and destiny, as the character's new identity as the Heir of Merlin may be tied to some greater purpose in the wizarding world.
Another power could be the ability to communicate with magical creatures on a deeper level. Since Merlin was said to have a great understanding of all things magical, the heir in fanfiction might be able to gain the trust and cooperation of creatures like centaurs and unicorns more easily than others.
One common theme is the exploration of power. Since Jim is the heir of Merlin, there's often a focus on the new powers he gains and how he learns to control them. Another theme is identity. Jim has to reconcile his identity as the Trollhunter with this new identity as Merlin's heir. Also, friendship is a big theme. His friends' reactions and how they support or sometimes question him in this new role.
Another possible candidate in fanfictions could be Neville Longbottom. He has a deep connection to the magical world and shows great courage and growth throughout the series. His latent magical abilities, which are finally fully realized, could be interpreted as him being an heir of Merlin in a way. He has the potential to be a great wizard, just like Merlin was.
A common theme is the power of magic. Since both Harry and Merlin are associated with magic, fanfictions often explore different aspects of magic, like how they can combine their powers or learn from each other's magical abilities. Another theme is friendship. They come from different time periods but still form a strong bond in many stories.
A prevalent theme is the exploration of magic itself. How the magic in the Harry Potter universe and that in the Merlin universe are related or different. Also, destiny plays a role. Fanfictions often explore how their destinies are intertwined, whether it was meant to be that they meet and change the course of events in both their worlds.
One common theme is the clash of magical cultures. Since Harry comes from Hogwarts and Merlin from Camelot, their different ways of using magic often create interesting situations. Another theme is friendship. The stories usually show how Harry and Merlin form a strong bond despite their different backgrounds.
One common theme is self - discovery. Harry realizing he's Gryffindor's heir makes him question who he really is. Another theme is power. Discovering this new heritage often gives Harry new powers or abilities related to Gryffindor. For example, he might have access to unique spells or magical items.
In 'Harry heir of Ouranos' fanfiction, the theme of self - discovery is very common. Harry has to figure out what it means to be the heir of Ouranos. There are also themes related to the rewriting of history or prophecies. His new heritage might change the way certain events were supposed to unfold. Another theme could be the clash between the wizarding world and the ancient powers associated with Ouranos, which can lead to some intense and unique storylines that are quite different from the original Harry Potter stories.
One common theme is the discovery of long - lost secrets. Since the heir is related to the founders, they often uncover things that have been hidden for centuries, like secret chambers or ancient spells.