For Professor Layton, you could explore his past a bit. Maybe there was a particular event in his childhood that made him so interested in puzzles and mysteries. Reveal this through flashbacks during the fanfic. For Luke, develop his relationship with other characters in the story. Let him interact with people from different backgrounds and show how he adapts. He could also learn new skills from these interactions, like a new way of looking at puzzles. Also, show his emotional side more, like his fear when in a dangerous situation and how he overcomes it.
To develop Professor Layton, you can focus on his intellectual side more. Show how he analyzes every situation and how his vast knowledge helps him make decisions. For Luke, you can show his growth. Maybe at the start he's a bit timid in solving really difficult puzzles, but as the story progresses, he becomes more confident. For example, you can have a scene where Luke is the one who figures out a crucial puzzle all by himself.
In a Professor Layton x Luke fanfic, to develop Professor Layton, you can give him some weaknesses. Maybe he's not so good at physical tasks. This can create interesting situations where Luke has to step in to help. For Luke, you can show his curiosity evolving. At first, he might be just following Professor Layton out of admiration, but later he starts to have his own questions and quests. You can also develop their relationship by having them argue about the best way to solve a problem. This shows their different perspectives and how they can learn from each other.
Chapter 199, "Good News Keeps Coming for the Hong Gang Family (Part 2)", is the clearest early answer because it turns Zhao Yuanwu's situation into a concrete plot event. Early on, Husband Hong Gang is the captain of the Green Wolf Team of the.... By the end, Middle-aged women like her were nonexistent.. Inside the broader power growth storyline, the chapter exposes hidden motives around Zhao Yuanwu, so readers can finally see how the conspiracy layer of the plot is actually moving.
Chapter 242, "Trouble at Long Mountain, You Arrived Too Late", is the clearest early answer because it turns Xia Chuan's situation into a concrete plot event. The setup is North of Wushuang Giant Stone Camp, snowfield., but the pressure keeps building through A small figure in a yellow cloak was desperately fleeing northward....
Chapter 191, "Repelling the Enemy and Punishment, The 1st Wedding", is the clearest early answer because it turns Xia Hong's situation into a concrete plot event. The chapter gives readers a real answer by opening on He remained silent, and Chen Yingba below could only continue to bow,... and ending on The exact strength of the Hive Camp, he was unsure..
Chapter 97, "Cloud Jiao Advances, Beast Blood Consumption", is the clearest early answer because Intermediate Cold Beasts finally turns buildup into a real advancement. Early on, When Xia Chuan returned to the camp with nineteen people and that.... By the end, First place, Cloud Jiao Team: 44,300 (Intermediate) Second place,....
Chapter 193, "The Army, The Beast Tide, Little Snow Mane", is the clearest early answer because it turns Xia Hong's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Population really is the cornerstone!" In the back of the main hall,... and follows through with Those Cold Beasts are all headed into the Arrow Bamboo Forest and....
Chapter 186, "White Bear, Mountain River Team, Stranger", is the clearest early answer because it turns Yue Feng's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Seven days ago, Lord's Cloud Jiao Team hunted an Intermediate Blue... and follows through with Even though Yue Feng's side had fewer people, their posture appeared.... By the close, Let's just do our best;
Chapter 246, "White Dew Gu and Cold Apple Jade Dew, Hanqiong's Sinister Smile", is the clearest early answer because it turns Xia Hong's situation into a concrete plot event. A useful checkpoint is the way the scene starts with On the day of April 16th, the Minister took a few of us to... and follows through with Sizzle..." A faint sizzling sound immediately came from within him,....
Chapter 188, "Venting, Drawing Lines, Preparations", is the clearest early answer because it turns Yue Feng's situation into a concrete plot event. The chapter turns that into something concrete by moving from Chen Yingba hadn't finished speaking when he saw Xia Hong flick his... to Leader, you're amazing!" "That Chen Yingba was so arrogant just now,.... What makes it stick is that the chapter closes with "The leader didn't strike fatally and let him go;
Chapter 235, "The Might of the Longyou Army, Yang Lu's Desperate Plight", is the clearest early answer because it turns Yangyuan Peak's situation into a concrete plot event. The chapter turns that into something concrete by moving from On the night of April 14, Xia Hong indeed personally witnessed the... to First take some interest for He Tu, die!" Li Xuantiang's voice was....
Chapter 290, "Bountiful Harvest—Store Land or Store People", is the clearest early answer because it turns Great Xia's situation into a concrete plot event. The chapter turns that into something concrete by moving from Under Wushuang's command, aside from the Cloud Dragon Army, there was... to The ultimate goal of the Great Xia is to destroy the three thousand....