For a good character interaction between Garou and Saitama, start with their fundamental differences. Saitama is a hero who is bored with the lack of challenge, while Garou hates heroes. Have them start with a fight, but make it a comical one where Saitama's nonchalance annoys Garou to no end. This can lead to some great dialogue exchanges where Garou tries to taunt Saitama into taking him seriously, but Saitama just doesn't care.
Garou from OPM might also work well. His ideology of being a 'human monster' and his constantly evolving strength could make him a formidable foe for Saitama. Their clash could be not only about physical strength but also about their different views on what it means to be a hero or a monster.
Another interesting concept is a crossover where the villains from the OPM world are a threat to Saitama's own world. Saitama then has to team up with the OPM heroes to fight back. This could lead to some really cool fight scenes and interactions between different characters.
Character development is a big part of these fanfics. Since both characters have their own fan bases, the writers try to stay true to their original personalities while also adding new layers. For example, Garou's struggle between his anti - hero ways and his potential for good can be further explored in relation to Metal Bat's more straightforward sense of justice. And the action scenes in these fanfics are usually intense, given the combat - ready nature of both Metal Bat and Garou.
Some smaller, more niche fanfic communities or forums dedicated to the source material of Suiryu and Garou might also be a good place to find such fanfics. You can ask around in those communities for recommendations or search through their story archives.
A fanfic could explore a world where Suiryu and Garou are from different dimensions. They meet by chance and have to figure out how to get back to their respective worlds while also dealing with their own personal growth and the challenges that come with their encounter.
You can find 'opm x bnha fanfic' on popular fanfic websites like Archive of Our Own (AO3). It has a large collection of fan - made stories from various fandoms, including the crossover of One Punch Man and My Hero Academia.
One great 'opm x bnha fanfic' is 'Powerful Alliances'. It has an interesting plot where characters from One Punch Man and My Hero Academia interact in a unique way. The character development is well - done, especially how they combine their different powers.
Well, in the fanfiction, the moment when Cosmic Garou tries to counter Saitama's attacks with his own new - found cosmic powers is really exciting. He has evolved to a whole new level, and seeing how his powers match up against Saitama's is a big part of the thrill. Maybe he creates some sort of cosmic energy blast that Saitama has to dodge or block in an unexpected way.