Common themes include the exploration of their different yet somewhat similar pasts. Both Harry and Gaara have had difficult upbringings with a lot of loneliness and misunderstanding. Also, the theme of power - how they use their unique powers in new situations when they meet each other. For instance, Gaara's sand powers could be used in the wizarding world in some really creative ways, and Harry's magic could be a novelty in Gaara's world. And of course, friendship is a big theme as they learn about each other's worlds and find things to admire in one another.
Well, there are several. The first one that comes to mind is the theme of redemption. Both characters have had their share of darkness in their lives. Harry had to deal with Voldemort and the temptation of the Dark Arts, and Gaara had his own inner demons with the Shukaku. In these fanfictions, they often help each other find a path towards redemption. Another theme is the discovery of new cultures and magic. Since they come from two very different fictional universes, there's a lot of room for exploring how they react to each other's ways of life, magic, and values. Additionally, the theme of facing challenges together is quite common. Whether it's fighting a common enemy or just dealing with the confusion of being in a new world, they support and learn from each other.
Power and its implications is also a frequent theme. X23 has her mutant powers, and in the Harry Potter world, there is magic power. Fanfictions may explore how these different forms of power are perceived, how they can be used for good or bad, and how the characters with these powers are treated by society. For example, X23's powers might be seen as dark magic in the wizarding world at first, and the story could be about how she proves that she is not a threat but an ally.
A common theme could be the unexpected connection between them. Since they come from different villages, exploring how they bridge that gap is often seen. Another theme might be Himawari's positive influence on Gaara, perhaps helping him open up more.
The theme of redemption also appears sometimes. Gaara's past actions and his journey to redemption can be intertwined with his relationship with Lee. Lee's positive influence on Gaara and vice versa, in terms of helping each other grow and become better shinobi, is a common thread in these fanfictions.
The theme of mutual respect is prevalent too. They come from different villages with different values, but in the fanfictions, they gradually respect each other's ways and grow together as a result.
Love and acceptance are very common themes. Gaara has had a difficult past, so in these fanfictions, the reader often helps him to accept himself and his feelings. For example, in many stories, the reader is the one who shows Gaara that he is worthy of love.
Time - travel is also a fairly common theme. Fanfic writers often use time - travel to bring Harry and James together in the same time period, leading to all sorts of interesting interactions. It allows for the exploration of their relationship in a new light, like how they would get along as peers rather than father - son. And of course, there's the theme of magic itself. How their combined magic could be used to solve problems or face new threats that the wizarding world might encounter.
One common theme is redemption. Since Lily died in the original story, in fanfiction she often gets a chance at redemption, like making up for lost time with Harry. Another theme is the power of love. Their relationship is a strong display of love's power, which can overcome many difficulties.
One common theme is power. Since Zeus is a very powerful god in Greek mythology and Harry has his own magical powers in the Potterverse, stories often explore how their combined powers can be used, either to face a greater threat like Voldemort or to bring about some kind of change in both the wizarding and godly worlds.
One common theme is the expansion of magic. Since Hecate is a goddess associated with magic, fanfictions often explore new types of magic that Harry could learn from her. Another theme is the idea of guidance. Hecate usually takes on a role of guiding Harry in these stories, whether it's in his magical studies or in dealing with the challenges he faces at Hogwarts and beyond.
One common theme is the power dynamic. Given the Enchantress' abilities, there's often exploration of how her power compares to Harry's and how they work together or sometimes clash because of it.