Some smaller, more niche fanfic communities dedicated to the relevant series might also have 'garou x metal bat fanfic'. You can try searching on forums or social media groups related to the series. However, these might not have as extensive a collection as the larger fanfic websites.
You can start by looking on fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfics from various fandoms, and there are likely to be quite a few 'garou x metal bat' ones there. Just use the search function and type in the relevant tags.
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.
There is also 'Metal and Fang'. In this fanfic, it focuses on how Metal Bat and Garou start off as rivals but gradually come to understand each other's motives. It's quite interesting as it delves deep into their personalities and how they might interact in different situations.
One idea could be a story where Garou and Metal Bat are forced to team up against a common enemy stronger than they've ever faced. They start off hating each other but gradually learn to respect each other's fighting styles.
There's a fanfic titled 'Garou and Metal Bat: A New Understanding'. In this story, they start off as rivals but as the plot progresses, they realize they have more in common than they thought. It shows their journey from hostility to a sort of friendship, with some great action scenes in between.
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.
One idea could be that they start off as rivals but are forced to team up against a common, even more powerful enemy. As they fight side by side, they gradually gain respect for each other's fighting abilities.
How about a plot twist where Garou suddenly loses his powers. Metal Bat, who has always seen Garou as a powerful adversary, now has to protect him. This forces them to work together in a new way and also makes Metal Bat re - evaluate his perception of Garou.
In the fanfiction, put them in various challenging situations. For example, they are trapped in a maze - like place. Metal Bat has to rely on Garou's survival skills, and Garou has to rely on Metal Bat's brute strength at times. Through these experiences, they both change. Metal Bat becomes more patient and Garou becomes more open to the idea of not being a complete outcast. This way, their characters develop in a natural and engaging way.
Well, the fanfiction could focus on a training arc between them. Imagine Garou, who has his own unique fighting style, teaching Metal Bat some new moves. In return, Metal Bat could teach Garou about the importance of protecting the weak. Their relationship could develop from a mutual dislike to a begrudging respect and then to an actual friendship. This could lead to them fighting side - side against the various threats in the One Punch Man universe, and they might even change the public perception of Garou from a villain to an anti - hero.
You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of various fanfics, including 'bat tf fanfic'. Just use the search bar and type in 'bat tf' and you'll likely find several relevant stories.