The theme of justice is often present as well. Given that she is in prison for a crime she may or may not have committed, fanfictions may explore the idea of seeking true justice. This can involve her trying to prove her innocence or fighting against the corrupt prison system, which makes for some exciting storylines.
There are fanfictions that depict little Jolyne's growth as a character. For example, some stories may show how she overcomes various challenges in the prison using her unique Stand abilities in different ways than in the official story. It gives readers a fresh perspective on her capabilities.
There's no way to really tell if it's common specifically for someone named Jojo. However, in general, reading fanfiction is a popular activity among fans of many different franchises. The Jojo series has a large and dedicated fan base, so it's likely that there are fans named Jojo who partake in reading fanfiction, but we can't say for sure how common it is without more data.
Perhaps this Jojo is interested in exploring different interpretations and stories within the Jojo universe that fans have come up with. Fanfiction often takes the existing characters, settings, etc. from the original Jojo series and creates new and unique storylines. So, this Jojo might be a big fan of the series and wants to see what other fans have imagined.
It depends. Maybe there are some telltale signs or elements that suggest it's a JoJo reference fanfic, but without specific context, it's hard to say for sure.
The JoJo manga is mainly in black and white. Colored versions exist but are not the norm. Sometimes, colored illustrations are done for promotional purposes or by fans.