Darkness is a very common theme. Since both characters are from dark and often disturbing origins, fanfictions usually revolve around their dark deeds and the overall gloomy atmosphere they create.
Another common theme is the exploration of their relationship. Whether it's a partnership in crime or a more complex, psychological bond, a lot of fanfictions focus on how they interact with each other. It could be a love - hate relationship or a symbiotic one where they rely on each other's skills in their dark pursuits.
Isolation is also seen often. Both Jeff the Killer and Laughing Jack are rather solitary figures in their own ways. Fanfictions might explore how they deal with their isolation when they come together. Maybe they find some sort of understanding in each other's loneliness or perhaps it just makes their relationship more strained.
Chapter 255, "Daton Festival", is the clearest early answer because it turns Uncle Zhao's situation into a concrete plot event. The chapter turns that into something concrete by moving from Sounds pretty interesting." "I know this one!
Chapter 359, "You Know Who I Am and You Dare Speak to Me Like This?!", is the clearest early answer because it turns Ye Chu's situation into a concrete plot event.
Chapter 92, "Why would a 19-year-old girl read this kind of book?!", is the clearest early answer because it turns West District's situation into a concrete plot event.
Chapter 224, "Won't You Consider Introducing Me?", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event. The chapter gives readers a real answer by opening on Jiang Li, ranked number one, was directly taken by the staff to an...
Chapter 335, "Songyang Ridge, Seven Houses Surrender, First Batch of Silver Arrives", is the clearest early answer because it pushes Xu Ning into a new phase or setting. Early on, The name "Songyang Ridge" was not given by Xu Ning; he discovered.... By the end, Ji Yang from Wanlong, representing the Six Families of Songyang....
Chapter 219, "Five Thousand Jin??!!", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Qi Tianyu was somewhat freaking out.
Chapter 348, "Schemes and Counter-Schemes, the Five of East Ridge, Zhu Yang's Threat, The Dust Settles (Part 4)", is the clearest early answer because it turns Yang Quan's situation into a concrete plot event. Early on, Upon hearing that Yanggu had sent someone first, Lu Yang raised his.... By the end, At this point in the competition, the champion is actually already....
Chapter 233, "Individual, Ten, Hundred, Thousand... Million, Ten Million, Damn!!!", is the clearest early answer because it turns Zhou Xu's situation into a concrete plot event. Early on, [What the hell, what's this about life span ending??.
Chapter 324, "Early Drills, Surge in Cold Resistance Level Members", is the clearest early answer because Cold Resistance Level finally turns buildup into a real advancement. A useful checkpoint is the way the scene starts with In terms of Cold Resistance Level numbers alone, there is no longer... and follows through with I'll inform the Lord now." "I'll handle it at once!" Finishing his....
Chapter 203, "She's Not Her Maid!", is the clearest early answer because it turns Director Qian's situation into a concrete plot event. It opens with Ah Fu knew he might have made a mistake, and after glancing at Su...