One common theme is the struggle between her kaiju nature and her human form. For example, in many stories, she has to deal with emotions and limitations that are new to her in human form.
Well, in a lot of mothra human fanfiction, the theme of environmentalism is quite prominent. Since Mothra is often associated with nature, stories might show how humans and Mothra team up to save the environment. Another common theme is discovery. The human characters might discover something new about Mothra, like a hidden power or a different side of her personality. Also, the theme of sacrifice can be found. Sometimes, either Mothra or the human has to make a sacrifice for the greater good.
A common theme is friendship. The human and Mothra often form a deep bond of friendship that helps them face challenges. Another theme is protection. They usually work together to protect the Earth from other threats like other kaiju.
One common theme is deception. Since Kyubey is known for being manipulative in the original series, in human form he often uses his appearance to deceive others, especially when it comes to recruiting magical girls.
Well, identity crisis is very common. Sonic is used to being a blue hedgehog with super speed, but when he becomes human, he has to re - evaluate who he is. Adaptation to a new physical form and a different set of abilities or lack thereof is also a theme. And then there are the themes of friendship and love. His relationships with his friends might change, and he might even find new romantic interests in his human form. For example, in some fanfictions, Sonic has to learn how to communicate his feelings in a more human way, which was not necessary when he was a hedgehog.
One common theme is his adjustment to the human world. Since he's from a different form originally, how he copes with human emotions, relationships, and society is often explored.
There's also a story where Mothra's human form teams up with other kaiju in human form to protect the world. It delves deep into her relationships and the challenges she faces in a more human - like world. In this fanfiction, Mothra's human form uses her elegance and grace to negotiate with the other kaiju.
One common theme is cooperation. Since they are both powerful creatures, seeing them work together against a common foe is often explored.
One common theme is the idea of two different species coming together. Godzilla and Mothra are very different in nature, so the fanfiction often explores how they overcome those differences. Another theme could be sacrifice, like one of them sacrificing for the other in a battle or difficult situation.
Common themes could include the impact on the monster ecosystem. With new life on the way, it might disrupt the balance of power among the various monsters. There could also be a theme of sacrifice. Maybe one of the parents has to make a great sacrifice to ensure the survival of the unborn. Additionally, the fanfiction might explore the concept of family in the context of these giant monsters, which is very different from the traditional human family concept.
One common theme is cooperation. Since they are both powerful creatures, many fanfictions explore how they can work together. Another theme is the balance of power. Writers often play with the idea of who is stronger and how that affects their relationship.