The main character is Naruto, but we can't forget the other ninja in Konoha. Characters like Shikamaru, who could help Naruto strategize based on his new skills and heritage. And Hinata, who might have a different relationship with Naruto considering his connection to Qrow. There could also be antagonists from both the Naruto world and potentially from Qrow's world if they oppose Naruto's new - found power or the implications of his heritage.
There would be Naruto's family in the fanfiction. Even if Qrow is his father, there could be a whole backstory about his mother. And then there are the elders in Konoha. They would be very interested in Naruto's new connection. They might try to use it for the village's benefit or be suspicious of it. And of course, any characters from Qrow's story that the author wants to introduce to create more drama or action in the fanfiction.