One common theme is the exploration of an unexpected relationship. Since Buffy and Marty are from different 'worlds' in a sense, their relationship is full of surprises.
You can try some popular fanfic websites like Archive of Our Own (AO3). It has a large collection of fanfics, and you're likely to find a good number of Buffy and Marty ones there. Just use the search function and type in their names.
One great Buffy and Marty fanfic is 'Buffy and Marty's Adventure'. It has an interesting plot where they team up to fight a new kind of supernatural threat in their town. The characters are well - written and it stays true to their personalities from the original shows they are from.
One popular 'Buffy x Marty' fanfic is 'A Different Kind of Meeting'. It explores an alternate universe where Buffy and Marty meet in a really unique situation. The author does a great job of developing their relationship in a new and exciting way.
Well, Saving Marty isn't a graphic novel. Usually, a graphic novel has a lot of illustrations and visual elements, but Saving Marty doesn't have those typical features.
I'm not sure who Marty Markowitz specifically is. There could be many people with this name. Maybe he's a local figure in a certain community, an entrepreneur, or someone with a unique personal journey. Without more context, it's difficult to tell his real story.