Another theme is the idea of unlikely alliances. Characters from the two series, who are very different in nature, have to come together. For example, wizards used to a certain way of life in Harry Potter might have to work with Mercy, a coyote - shifter. This creates a lot of interesting relationship dynamics. The characters must learn to trust and rely on each other despite their differences. It also often involves a struggle for power or against a greater evil that spans both universes, forcing them to put aside their differences and fight together.
One common theme is the clash of different magical cultures. In these crossovers, you often see the structured magic of Hogwarts contrasted with the more primal and nature - based magic in Mercy Thompson's world.
Family is another important theme. It shows how the baby brings the family closer together, including Mercy's relationship with her mate and the extended pack family. The fanfics explore how they all support each other in raising the baby.
I've also heard of 'Potter and Thompson: An Unlikely Alliance'. In this fanfiction, Harry Potter and Mercy Thompson team up to face a common enemy that threatens both their worlds. It's a long read but full of action and interesting character development as they learn about each other's abilities and cultures.
A major theme is the exploration of the unknown in the supernatural world. Fan fictions often take Mercy on adventures to discover new places and creatures. Another theme is the concept of family. Mercy has a complex family situation, and this is often explored in different ways. Additionally, the theme of self - discovery is very common. As Mercy faces new challenges, she learns more about herself and her capabilities, which is a central aspect in a lot of Mercy Thompson fan fiction.
One common theme is the clash of cultures. The ninja - like Akatsuki with their own values and traditions coming into the very different wizarding world of Harry Potter. Another theme is power struggles. Akatsuki members are often power - hungry in their own universe, and in the Potter world, there are different power dynamics with the Dark Lord and the Ministry of Magic.
One common theme is the clash of different worlds. For example, when Harry Potter is rescued in a crossover with another universe, like the Star Wars universe, there's a lot of focus on how the magic of Harry's world interacts with the technology and different species in Star Wars. It's about two very different concepts trying to coexist.
One common theme is cultural exchange. Since Hetalia is about different nations, when combined with Harry Potter, it often shows how the different cultures of the Hetalia characters interact with the magical culture of the Potterverse. For example, how they react to magic spells compared to their own 'powers' in Hetalia.
One common theme is the clash of different magical systems. Harry Potter has its own brand of magic with wands and spells, while Buffy has slayer powers and a different kind of magic related to demons and the supernatural. Fanfictions often explore how these two types of magic interact when the characters meet.
A common theme is the clash of different magical systems. The conjuring skills from one world and the magic in Harry Potter are very different. So often there's a theme of characters trying to understand and adapt to the new magical rules. For example, in many fanfics, a conjurer might struggle to understand how spells work in Hogwarts compared to their own conjuring methods.
The theme of identity is also prevalent. The fem Harry Potter has to figure out who she is in a world that has certain expectations. With the crossovers, there are additional factors that influence her identity. She might have to balance her Hogwarts self with the new elements introduced from the other fictional universes she is crossed over with.
Power is a major theme. How the powerful characters from both universes interact and deal with power is often explored. For example, characters like Voldemort and Rhysand might be pitted against each other in some fanfictions. Friendship is also a theme, as characters from both sides form new alliances. In many stories, a Hogwarts student might become friends with a fae from Acomaf, and they learn from each other's strengths and weaknesses.