The theme of adaptation could be quite common too. The human might need to adapt to the strange environment or culture associated with the Tempest. Or vice versa, the Tempest might have to adapt to human ways. This can lead to interesting character developments and plot twists. There could also be themes related to friendship or even love that develop between the two, despite their differences.
Friendship is also a big theme. As with the overall My Little Pony franchise, fanfics often show Tempest forming new friendships and learning the value of it. For example, she might start off as a loner but gradually open up to other ponies.
I'm not sure about specific 'Tempest x Human' fanfics. But you can try searching on popular fanfic platforms like Archive of Our Own. There are likely to be various works there.
One common theme is the exploration of different worlds. Since Tempest and Twilight have their own unique settings, fanfics often focus on how these worlds interact or contrast.
A frequent theme is the power of their bond. In the show, they are a strong team, and in fanfics, this can be explored on a deeper level. It could involve them facing new threats together and relying on each other more than ever. Also, themes of love and friendship are common. Some fanfics might focus on a romantic relationship developing between a human Senketsu and Ryuko, while others might emphasize their platonic but extremely strong friendship. There can also be themes related to the acceptance of differences, as Senketsu's nature is quite different from Ryuko's, and how they overcome any prejudices or misunderstandings in the fan - created stories.
Common themes often revolve around loyalty. Glaceon could be fiercely loyal to the human it befriends, and the human could also show unwavering loyalty. There's also the theme of adaptation. The human has to adapt to the world of Pokémon where Glaceon lives, and Glaceon might have to adapt to human ways. Additionally, there could be a theme of cooperation. They work together to achieve a common goal, whether it's saving a Pokémon in trouble or finding a rare item in the Pokémon world.
Some 'female nergigante x human' fanfics may also have a theme of transformation. Maybe the human character is influenced by the nergigante in some way, either physically or mentally, and this transformation becomes a central part of the story. It could be a slow process that changes the human's perspective on life and the world around them.
Common themes include the power of friendship and love to bridge divides. In many 'Blood Elf x Human' fanfics, the two characters start off not understanding each other but through shared experiences, they grow closer. There's also the theme of sacrifice. Sometimes, to be together or to protect each other, one or both of the characters have to sacrifice something, like their standing in their own race's society. And cultural exchange is often there, as they learn about each other's traditions and ways of life.
The theme of transformation can also be common. Sometimes the human might gain some dragon - like abilities or the dragon might take on more human qualities as they interact. Another theme is the struggle against society's norms. Since their relationship is not typical, they often have to fight against the expectations and prejudices of their respective species' communities. This adds a layer of drama and conflict to the fanfics.
Transformation is also a common theme. Sometimes the male human may be in danger of being turned into a werewolf, or the female werewolf may try to suppress her werewolf side for the sake of the relationship. Additionally, the idea of loyalty is often explored. The female werewolf's loyalty to her pack and how that conflicts or aligns with her loyalty to the male human, and the male human's loyalty to the female werewolf in the face of potential danger from other humans or werewolves.
One common theme is redemption. Since Tempest has a more troubled past, many fanfictions focus on her journey towards redemption with Twilight's help. Another theme is friendship. They are two very different characters, so exploring how they become friends is popular. For example, they might start off as strangers or even enemies and then develop a deep bond.