Obviously, the Black Arrow himself is a main character. He is usually depicted as a skilled archer and a brave fighter.
There could also be antagonists. A cruel warlord or a devious sorcerer who wants to stop the Black Arrow from achieving his goals. These characters add conflict and drama to the fanfiction stories.
Not having read 'the black arrow graphic novel', it's difficult to name the main characters precisely. However, it's common for a graphic novel to have a central character with a unique personality. This character might be an outcast or a chosen one who is drawn to the black arrow. There could be supporting characters like a loyal friend who stands by the main character's side throughout their adventures with the black arrow, and an enemy who has a long - standing feud with the owner of the black arrow.
The main protagonist from the original 'the black arrow' is likely to be very popular in the fanfiction as well. Their heroic deeds and journey are often the focus.
The main characters are Green Arrow and Black Canary.
There could also be a villain. The villain would oppose the protagonist and create conflicts and challenges for the hero to overcome. Their actions would likely be the source of much of the drama in the novel.
It could be two star - crossed lovers from different social classes. One could be a noble and the other a commoner, and the love arrow brings them together against all odds.
The Arrow is sure to be a main character. In addition, Hawkeye would be a crucial character in this fanfiction. Since they both are archers, there could be a lot of interaction between them, like competing or collaborating in archery - related tasks. And of course, Captain America with his leadership skills would also be among the main characters to lead the team that now includes the Arrow.
Oliver Queen, of course. As the main character of Arrow, he is central to most crossovers. His skills as the Green Arrow and his complex personality make him a prime focus.
It's difficult to say without reading the fanfiction. However, considering the Arrow series, it might be centered around Oliver. Or perhaps it could be about other characters like Diggle or Thea, and their love interests within the context of this waiting - game - like love story.
Sasuke might also be a main character in such fanfiction. His Sharingan and his own strong chakra could potentially be used in relation to the chakra arrow. He could use his Sharingan to predict the path of the chakra arrow or enhance its power.
Obviously Naruto is one of the main characters since it's in the title. There might also be his friends like Sasuke or Sakura. They could be either helping Naruto in his skewer - arrow adventure or be in need of his help.