Often, there is the theme of inspiration. Deku is very inspiring in the original story, and in fanfiction, he can inspire Shoto to be a better hero. Also, self - discovery. They both are on a journey to discover more about themselves, their powers, and their place in the hero world. In fanfiction, this journey can be elaborated on in different and interesting ways.
One common theme is redemption. Dabi, with his troubled past, often has a journey towards redemption, and Shoto can play a part in that. Another theme is family. Given their complex family relationships in the original story, fanfics often explore how they deal with family issues together.
No, it is not appropriate. Creating or distributing sexual fanfiction involving underage or fictional characters in a sexual context is unethical and often violates the terms of use of various platforms. Such content can also be considered a form of inappropriate objectification.
Well, 'shoto todoroki abused fanfiction' might be centered around the idea of taking the character Shoto Todoroki from the original source material and putting him in an abusive context. This could be physical, emotional, or psychological abuse. Some writers may use this as a means to develop the character further, to show his strength in overcoming such difficult situations, or it could be a way to delve into the darker sides of the fictional world in which he exists. It could also be a form of expressing the writer's own creativity and interpretation of the character's potential experiences.
One common theme is the exploration of gender roles. Since Shoto is typically male in the original, making her female in fanfiction often leads to an examination of how she navigates a world where male heroes are more common. For example, she might face different expectations or challenges.
One common theme is growth. Both Shoto and Momo are often shown growing as individuals and as a couple. For example, they might learn to overcome personal insecurities with the support of each other.
One common theme is friendship turning into something more. They often start as just friends or acquaintances and then develop deeper feelings. Another theme is the contrast between their personalities. Shoto is often seen as more reserved while Vox is more outgoing, and how they balance each other out is a big part of the stories.