It's possible that antagonists from both the 'Fate' universe and the crossover universe are main characters too. They could be working together or separately against Emiya. For example, an evil mage from the 'Fate' world and a powerful villain from the crossover world might team up to stop Emiya from achieving his goals.
Obviously, Counter Guardian Emiya is one of the main characters. He will be at the center of the story, driving the plot with his actions and decisions. There could also be characters from the world he is crossing over into. For instance, if it's a crossover with a popular shonen anime world, there might be the protagonist of that world who will interact with Emiya.
Supporting characters from the 'Fate' series might also make an appearance. Characters like Rin Tohsaka or Archer could be involved. Their relationships with Emiya add depth to the story. In the crossover aspect, perhaps there are side characters from the other universe who play important roles in helping or hindering Emiya's journey.
Chapter 323, "This Person Has Ulterior Motives", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. A useful checkpoint is the way the scene starts with There's such a nuance to all this?!
Chapter 353, "He's Lying!", is the clearest early answer because it turns Miss Liu's situation into a concrete plot event. The chapter turns that into something concrete by moving from The three of them turned their heads together.
Chapter 396, "The Shang Family Now Follows My Orders", is the clearest early answer because it turns Shen Lan's situation into a concrete plot event. Early on, Doomsday Beehive" featured a male supporting character who was.... By the end, It seems she was truly out of options..
Chapter 368, "You Don't Deserve to Be My Mother", is the clearest early answer because it turns Lin Manru's situation into a concrete plot event. It opens with I haven't detained anyone, how could I possibly detain him?
Chapter 419, "Survival of the Fittest, Only the Strong Survive", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Soon, these two leaderboards were also synchronized to Weibo in real...
Chapter 545, "Kiss Me", is the clearest early answer because it turns Shang Shaojing's situation into a concrete plot event. Early on, Truth or dare, I still choose dare!" He just didn't believe it, Jiang.... By the end, I was wondering why you were so sheepish around us, I thought you had....
Chapter 440, "You Know Fengshui Array?!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from The scorching afternoon sun, wrapped with moist sea breeze, ascended...
Chapter 428, "Stunning Debut!", is the clearest early answer because it turns Another Youth Trainee's situation into a concrete plot event.
Chapter 236, "The Murderer Returns to the Scene of the Crime Theory", is the clearest early answer because it pushes Jiang Li into a new phase or setting. A useful checkpoint is the way the scene starts with The short-haired youth beside them chimed in, "That's right, senior,...
Chapter 596, "Then Blow Them All Up", is the clearest early answer because it turns Zhao Lang's situation into a concrete plot event. Early on, Jiang Li shook his head without any expression.. By the end, They were stunned for a few seconds before they rushed toward Jiang....