Depending on the plot of the fanfiction, there could be a love interest for Pain's daughter. This character could be from a different clan or village. Their relationship could be a key aspect of the story, with all the challenges that come from their different backgrounds and the situation of the ninja world.
One interesting story could be about Pain's daughter growing up in the Hidden Rain Village. She might have unique powers that set her apart from others in the village. Maybe she tries to understand her father's actions and has a moral struggle within herself.
In the fanfiction, perhaps other characters could offer kind words and physical comfort. For example, a close friend could hold the pain's hand and tell them that everything will be okay. The friend might also share their own experiences of dealing with similar situations to make the pain feel less alone.
It could be an original character created just for the fanfiction. Maybe a mysterious ninja woman who crossed paths with Kakashi during a mission and they had a brief but intense relationship.
Well, Naruto and his twin oc are the central figures. But don't forget about the other Konoha ninjas. Shikamaru, for example, could befriend the twin and use his intelligence to help the twin in various situations. Hinata might also have a role, perhaps having a crush on the twin instead of Naruto this time. And of course, the Hokage, whether it's Tsunade or someone else, would be involved in governing the village and dealing with any issues that the twin or Naruto might cause.
Well, Naruto is obviously one of the main characters. He's the one who's going to be doing the beating. And Pain is also a main character in this context, as he is the opponent Naruto has to defeat.
It's hard to say without actually reading the fanfiction. But it could be the classic pairing of a male and female lead. For example, in a Twilight - inspired fanfic, it might be Edward and Bella where Edward kisses Bella's pain away. Or it could be two best friends who have a deeper connection than they realize at first.
Obviously, Naruto and Pain are the main characters. Naruto, the energetic and determined ninja from Konoha. Pain, on the other hand, is the complex antagonist with his own set of beliefs about peace through pain. Their interactions are likely to be the focus of the fanfiction.
Obviously, Naruto would be one of the main characters as it's about him being the son of Pain. Pain himself would also be a crucial character, even if he might not be physically present all the time. And characters like Sasuke, Sakura, and Kakashi would still likely play important roles as they are Naruto's friends and mentors in the original story and would have to interact with Naruto in this new, changed scenario.
I'm not sure specifically as it depends on the particular 'oc in the north fanfiction'. But generally, there could be a strong - willed protagonist who is trying to make a name for themselves in the north. Maybe a young adventurer who has left their home in search of something in the northern regions.
Since it's an 'oc fanfiction', the main characters would be the original characters made up by the author. In the context of 'wolves 2014', they could be wolves with unique personalities. Maybe there's a strong and brave male wolf who is the leader of the pack, or a female wolf with special abilities that help the pack survive in 2014.