This is highly inappropriate. Fanfiction should be a form of creative writing that adheres to ethical and moral standards. The show 'Zack and Cody' is aimed at a family audience, and creating fanfic with sexual content goes against the spirit of the original work and is unacceptable in a civil and respectful writing community.
I'm not sure about the common themes in 'Zack and Cody gay fanfic' specifically, but in general, for gay fanfic, themes like friendship turning into love, coming out, and dealing with acceptance might be present.
I'm not sure specifically as I haven't read it. But generally, it might be about the fictional sweet experiences and adventures of Zack and Cody in a relationship within the context of fan - created gay fiction.
Sorry, I'm not aware of specific 'Zack and Cody gay fanfic' as it may not be a mainstream or widely known type of fanfic. You could try searching on some dedicated fanfic websites.
One common theme could be the exploration of the characters' hidden feelings. For example, how Zack or Cody might discover their attraction to someone of the same sex in the hotel setting. Another theme could be the challenges they face in accepting their own identity within the context of the show's family - friendly and often comical environment.
Clearly, Zack and Cody are the main characters. In the fan - created story of 'the sweet life of zack and cody gay fanfic', they are the ones whose relationship and lives are being explored. Their individual personalities, which were established in the original work, are now being used to craft a new narrative about their gay relationship, including how they communicate, make decisions together, and face any external pressures.
A great theme would be their friendship. They could face a challenge that tests their bond, like when one of them gets in trouble at school and the other has to figure out how to help. It would focus on the positive relationship between the two characters without any inappropriate content.
One ethical consideration is respecting the original source material and its intended audience. If the original show was aimed at a younger or family - friendly audience, writing explicit or inappropriate fanfic might go against the spirit of the original. Also, when writing about gay relationships, it should be done in a way that is not fetishizing or stereotyping. It should be a legitimate exploration of character and relationship, not just for shock value.
I'm not sure if it's a 'popular' genre specifically. Fanfiction can cover a vast range of themes and relationships, but this seems rather niche and perhaps not as mainstream. It might have a small following among those who are really into exploring different relationship dynamics for the Zack and Cody characters, but it's not likely to be as widespread as more common fanfic themes like friendship or traditional romantic relationships.
There could be many fanfics about Zack and Cody that are family - friendly and focus on their adventures, friendships, or growth. For example, some might explore their experiences at the hotel they live in, their relationships with other characters like their mom or the hotel staff. You can look for such fanfics on popular fanfiction websites.