Most likely Naruto would be one of the main characters since it's in the title. But there could also be characters from the Naruto universe who are involved in his journey as the 'king of hollows'. Maybe Sasuke or Sakura might be there to support or oppose him depending on how the story goes.
In the 'naruto king of hollows fanfiction', Naruto is bound to be a central figure. However, we might also see some of the Naruto series' villains playing different roles. For instance, Orochimaru could be interested in Naruto's new power as the 'king of hollows' and try to either manipulate him or steal his power. And of course, Naruto's friends like Shikamaru or Kiba could also be involved, perhaps helping Naruto adapt to his new identity and the challenges that come with being the 'king of hollows'.
Chapter 815, "You've eaten through all the savings!", is the clearest early answer because it turns Jiang Cheng's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Jiang Zhao Yuan was quite surprised, "Right, absolutely right, haha,...
If you want the clearest chapter reference, go to Chapter 11. Early on, After a meeting, Shang Shaojing pinched the bridge of his nose, tired, and...; later, the chapter leans on How is it going with the Jiang Family?" The assistant looked troubled and....
Chapter 713, "Uncle Will Owe You for Life", is the clearest early answer because it turns Lili's situation into a concrete plot event. The chapter turns that into something concrete by moving from Jiang Li raised her head and was startled by Zhao Lang's smiling eyes.
Chapter 476, "Make a feint to the east but attack in the west, take something out of a bag effortlessly", is the clearest early answer because Jiang Yan gets a payoff that changes the stakes.
Chapter 613, "When a Whale Falls, All Life Thrives", is the clearest early answer because it turns Shaobai's situation into a concrete plot event. The chapter turns that into something concrete by moving from Hearing He Wen's words, Shen Lan was so excited she nearly sprayed...
Chapter 439, "Never Question Sister Li", is the clearest early answer because it turns Sister Li's situation into a concrete plot event. It opens with There was no helping it, she brought the man here, so even if he was...
Chapter 905, "I Plan to Quit the Circle", is the clearest early answer because it turns Is's situation into a concrete plot event.
Chapter 773, "I am the Trainee Here", is the clearest early answer because it turns Shiguang's situation into a concrete plot event.
Chapter 616, "I'm Going to Save Sister Xiao Wan!", is the clearest early answer because it turns Su Yinwan's situation into a concrete plot event. Early on, Since the storm had hit that morning, he had been preoccupied and out....
Chapter 537, "Ding, Jiang Cheng's affinity drops by 10 points!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. Early on, Miss Su Yinwan immediately hung her head in dejection.. By the end, In this regard, he still held a slight advantage..