You should start by researching the two universes thoroughly. If you're doing a 'Back to the Future' and 'Ghostbusters' crossover, learn about the rules of time travel in 'Back to the Future' and the technology and mythology of 'Ghostbusters'. After that, come up with a unique situation. For instance, the Ghostbusters could be called to Hill Valley because some time - travel - related ghosts are causing chaos, and Marty has to help them using the DeLorean.
First, decide which two (or more) universes you want to cross over. For example, if it's 'Back to the Future' and 'The Terminator', think about how the time - travel concepts in both will interact. Then, create a character - driven plot. Maybe the Terminator is sent back in time to Hill Valley to stop Marty from changing the future, but Marty has the DeLorean to outwit him.
Begin with a strong hook. In a 'Back to the Future' and 'Superman' crossover fanfiction, you could start with Superman seeing the DeLorean traveling through time and being intrigued. Then, you need to establish the relationship between the characters. Maybe Superman and Marty become friends and use their combined powers (Superman's abilities and the DeLorean's time - travel) to save both Metropolis and Hill Valley from a common threat that spans across different timelines.
Chapter 111, "A Turn of Fate [Triple-length Chapter]", is the clearest early answer because it turns Cold Beasts's situation into a concrete plot event. The chapter gives readers a real answer by opening on Even daring to make a small hole to peek, he didn't dare. and ending on Hold them back, the rest, keep running, quick!" Chen Ying didn't....
Chapter 169, "Trade, Bamboo Silk, Focus", is the clearest early answer because it turns Ice Abyss World's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Xia Hong was dumbfounded at this moment. and follows through with Noticing the expressions of Xia Hong and others, Yuwen Dao thought....
Chapter 142, "%, The Boiling Brought by the Martial Arts Training Ground [8000 Major Chapter Subscription Request]", is the clearest early answer because a shaky connection becomes usable in the plot. Early on, And those coming for the first time began to cultivate by imitation,.... By the end, It should only take one more day to finish them up." Xia Hong nodded,....
Chapter 193, "The Army, The Beast Tide, Little Snow Mane", is the clearest early answer because it turns Hunting Department's situation into a concrete plot event. Early on, Population really is the cornerstone!" In the back of the main hall,.... By the end, As for the army matter, that's even more wishful thinking..." Xia....
Chapter 136, "He Yuanhun, Yuwen Hu, Yuwen Dao (Three in One)", is the clearest early answer because it turns Xia Chuan's situation into a concrete plot event. It opens with Yuwen Dao, along with the nine behind him, looked at the iron arrow... and closes on Big Brother!" "Leader..." Seeing Xia Hong in hesitation, Xia Chuan....
Chapter 181, "What Does Great Xia Want, Liu Dahu's Ambition", is the clearest early answer because it turns Great Xia's situation into a concrete plot event. It opens with He turned his head to look at Zhu Xing and Meng Yuan, discovering... and closes on Initially, Qiu Peng didn't fully understand, but now he realized that.... The key payoff is that the chapter closes with "Leader Xiao, it's on the way, so come along with us.
Chapter 213, "Long Mountain News, Ecstasy, and Riot (Part 3)", is the clearest early answer because it turns Luo Ming's situation into a concrete plot event. Early on, This is what a clever person does!. By the end, There were seven people in the cave; those who planned to attack him.... Inside the broader family politics storyline, the chapter exposes hidden motives around Luo Ming, so readers can finally see how the conspiracy layer of the plot is actually moving.
Chapter 125, "Newborn, Yue Yuan", is the clearest early answer because it turns Great Xia's situation into a concrete plot event. The setup is As soon as Xia Hong and his group retreated, the area near the..., but the pressure keeps building through A hundred breaths later, within the Arrow Bamboo Forest, He Meng....
Chapter 177, "Population Growth, Trouble for Hong Guang【Big Chapter, Votes and Subscriptions Needed】", is the clearest early answer because it turns Zeng Fan's situation into a concrete plot event. It opens with Shi Ping possesses Earth-digging Realm cultivation and can bring so... and closes on Going back and forth shouldn't take long..
Chapter 74, "Easy Hunting", is the clearest early answer because it turns Snow Mane's situation into a concrete plot event. The chapter gives readers a real answer by opening on The cold wind was piercing, the silver-clad landscape pure white. and ending on Its long tongue severed, the fear and rage in the Snow Mane's pupils....