One aspect to consider in this fanfiction could be the power dynamics. If Yuichiro is dominant, it might lead to interesting character interactions with Mikaela. For example, Yuichiro could be the one making decisions in their adventures together, while Mikaela might play a more supportive role. It also adds an element of tension and drama to their relationship, as the dominant - submissive dynamic can create various scenarios for character growth and conflict.
It depends on how the author of the fanfiction has developed the plot and the characters. They could have given Natsu some special power - up or a unique situation that makes him stronger than Gildarts. For example, the author might have introduced a new form for Natsu that gives him an edge in combat, or perhaps they've weakened Gildarts in some way for the sake of the story. However, in the original series, Gildarts is extremely powerful, so this is a significant departure in the fanfiction.
The following are some recommendations for novels where the main character is stronger than the system:
1. The Self-Cultivation of the Male Lead. Author: Wen Ruo Bucheng
2. I'm the Common Villain in the Fictions, by Big Firepower and Small Gun
3. The Number One Strong Control in History. Author: Old Xu
4. Low-Dimensional Revolution, by Fat...
Please note that these novels may only partially meet your needs. You are recommended to search further for more relevant novel recommendations.
One common theme is the deep emotional bond between them. Given their relationship in the original work, fanfictions often explore how they support and care for each other on a more profound level. Another theme could be adventure, where they go on quests together and their relationship develops during those experiences.
I'm not that familiar with 'yuichiro hyakyua' crossover fanfiction, but often in crossovers, themes like friendship between characters from different worlds can be common. Maybe also the exploration of different powers or abilities when the characters interact.
Survival is also a big theme. When he is in a crossover with a more dangerous world, like a post - apocalyptic or a world full of powerful enemies, Yuichiro has to use his skills and wits to stay alive. It creates a lot of tense and exciting moments in the fanfiction.
In the 'izuku stronger than all might fanfiction', Izuku can be stronger for several reasons. Fanfiction writers often take creative liberties. They may write that Izuku has a deeper understanding of his quirk, One For All, compared to All Might. He could also have additional abilities or support from other characters that contribute to his increased strength. Maybe he has formed alliances with powerful individuals who help him train and unlock new levels of power, enabling him to surpass All Might.