One great story could be where the OC is a strong - willed martial artist who challenges Yujiro Hanma. Their interactions are filled with intense battles and mutual respect that gradually turns into a complex relationship.
First, understand the character of Yujiro Hanma. Know his personality traits like his extreme strength and pride. Then, create your OC with a distinct personality. Start with an interesting encounter between them, like a chance meeting at a fighting tournament.
Yes, Frankie Presto is fictional. It's a name that exists within the realm of imagination and creative storytelling. Maybe it's from a book, a film, or some other fictional medium.
I'm not sure specifically as it depends on the details within that particular fanfiction. It could be that they are two characters who have a special relationship, perhaps a romantic one, that the author is exploring in the context of the fanfiction's universe.
The best way to know where to start is to look for discussions on manga-focused websites. Fans often share their experiences and advice on continuing after the anime. Another option is to check social media groups dedicated to Baki Hanma to get suggestions from fellow fans.
Frankie and Johnny is purely fictional. The plot and characters are the imagination of the writer or creators, not based on any true accounts or real-life experiences.