There might be a lot of drama. Her old friends in the resistance would feel betrayed. They would likely try to either convince her to come back or stop her if they think she's become an enemy. And Kallen would have to struggle with her new identity and loyalties.
She could start to reform Britannia from within. Kallen is a strong - willed character. If she joins Britannia, she may try to influence the system to be more just. For example, she could work towards improving the treatment of the Elevens within Britannia's hierarchical society.
Chapter 537, "Ding, Jiang Cheng's affinity drops by 10 points!", is the clearest early answer because it turns Zhuola's situation into a concrete plot event. The chapter turns that into something concrete by moving from Miss Su Yinwan immediately hung her head in dejection.
Chapter 229, "He's Actually Brother Liu, the Watermelon Seller?!", is the clearest early answer because it turns Huo's situation into a concrete plot event. Early on, Huo Ziyang's face had already turned deathly pale.. By the end, Isn't it enough to teach a child a lesson when he makes a mistake?.
Chapter 606, "Are There Crocodiles?!", is the clearest early answer because it turns Ji Yanbai's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Hearing Ji Yanbai volunteer to stay behind, everyone ceased to have...
Chapter 400, "Arriving at Yan City", is the clearest early answer because it pushes Lili into a new phase or setting.
Chapter 586, "She Just Likes Men Who Show Weakness Initiative", is the clearest early answer because it turns Yu Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from Jiang Yan quickly swam over to the person.
Chapter 328, "Persuading the Old Master", is the clearest early answer because it turns Jiang Zhao Yuan's situation into a concrete plot event. The chapter turns that into something concrete by moving from Jiang Li's authoritative words stunned the old man.
Chapter 409, "I'm Feeling Lucky!", is the clearest early answer because it turns Nina's situation into a concrete plot event. It opens with Jiang Yan was still arguing with Yu Li with his hands on his hips,... and closes on She has been staring at you since just now." Jiang Li took a look at....
Chapter 291, "To Hell with Sister Complex!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event.
Chapter 387, "Hello everyone, this is my disciple", is the clearest early answer because a shaky connection becomes usable in the plot. A useful checkpoint is the way the scene starts with Liu Suqing V: "Even if we meet, I wouldn't recognize, faces covered...
Chapter 288, "The Old Master Already Knows", is the clearest early answer because it turns Senior Su's situation into a concrete plot event. The chapter gives readers a real answer by opening on Jiang Li and Zhao Lang were lifted onto stretchers and taken to...