A third common theme could be redemption. John Winchester made some mistakes in the series. In M M fanfics, his relationship with a male character might be a way for him to find redemption or a new purpose. Maybe through the support and love of this other character, he starts to heal from his past traumas and become a better person. This theme adds depth to the character and the fanfic as a whole.
Yes, there are quite a few. You can start by looking on fanfic platforms like Archive of Our Own. There, you might find various interpretations of John Winchester in gay relationships. Some focus on his character development in an alternate universe where his sexual orientation is different, exploring his relationships with other male characters in depth.
One common theme is the idea of the female character being a source of support for Sam. In many fanfics, she helps him through tough times, whether it's dealing with his past traumas or facing new threats. Another theme is the exploration of Sam's more sensitive side through his interactions with the female. It's like the female character brings out a different part of him. And often, there's a theme of a budding romantic relationship, which adds an interesting dynamic to the story.
A prevalent theme is the discovery of a new side of John. In love stories, his softer, more vulnerable side often emerges. Also, the theme of secrets is common. His love interest may have secrets related to the supernatural, and as they uncover each other's secrets, their relationship develops. For example, she might be part of a secret society that has its own way of dealing with the supernatural, and John has to navigate this new knowledge while falling in love.
One common theme is the idea of protection. John is often portrayed as a protector in these fics, shielding the reader from the dangers of the supernatural world. Another theme is the healing power of love. Their relationship is shown to help both John and the reader deal with their past traumas.
One common theme is the struggle between love and discipline. John loves his sons, but he also has to prepare them for the dangerous world of hunting. So, in fanfiction, there are often scenes where he has to be strict to teach them important skills or values.
Archive of Our Own (AO3) is a great place to start. It has a large collection of fanfics from various fandoms, and you can use the search function to look for John Winchester - related gay fanfics. Just type in 'John Winchester' and some relevant keywords like 'gay' or'male/male relationship' in the search bar.
One common theme is empowerment. Since it's a female - centered take on John Wick, the stories often show the female character being strong and capable in the dangerous underworld. Another theme is revenge, just like in the original John Wick movies.
The theme of acceptance is quite common. How the other characters accept or struggle to accept John's new form. And there's also the theme of adaptation. John has to adapt to the new body and the new social expectations that come with being a girl in the Homestuck setting. This can lead to some really interesting character development and plot twists in the fanfic.
Well, identity is a significant theme. The Winchester sister often has to figure out who she is in relation to her family and the hunting world. Also, sacrifice is common. She may have to sacrifice her own desires or safety for the greater good of her family or to save the world from supernatural threats. There's also the theme of friendship as she might make friends with other hunters or people in the supernatural world.
One common theme is protection. The cat often protects the Winchesters in some way, whether it's from physical harm like a demon attack or from more emotional harm by providing comfort during tough times. Another theme is mystery. Since the cat usually has some sort of special ability, it adds an element of mystery to the story as the Winchesters try to figure out what the cat is and how it can help.