One common theme is friendship development. Given their different backgrounds and personalities, stories often explore how they become friends. For example, Denji's more straightforward and sometimes naive nature might contrast with Kobeni's more timid and cautious self, and the fanfic could show how they bridge that gap.
Sure. You can start by looking on fanfiction.net. There are often a variety of fanfics featuring this pairing. Some might focus on their adventures together in the unique world they are from, exploring how their different personalities interact and complement each other during battles or in day - to - day situations.
No. Such content is inappropriate and often violates moral and ethical standards. Fanfic should focus on positive, healthy and family - friendly themes.
One story could be that a young gay man was in a very loving relationship. It was his first time, and he felt a mix of nervousness and excitement. His partner was very gentle and understanding, guiding him through it. It was a very intimate moment that deepened their connection.
No, it is not appropriate in most social and moral contexts. Such a story involves vulgar and inappropriate content that goes against the norms of respectful communication within a relationship and in society at large.