The Hogwarts Express could somehow be connected to the DeLorean. Maybe a powerful magic made the two vehicles fuse together. Harry, Ron, and Hermione could find themselves in the DeLorean instead of the Hogwarts Express on their way to school. They would then be thrust into the Back to the Future world. In this new world, they would have to use their magic skills to get back to their own universe while also helping Doc Brown and Marty with their problems, such as fixing the time - space continuum in the Back to the Future world.
Perhaps a spell gone wrong in the Harry Potter universe could open a portal to the Back to the Future universe. Hermione, being the brilliant witch she is, could team up with Marty McFly. They would have to learn about each other's worlds quickly. Hermione could teach Marty about magic, and Marty could show Hermione how to use the flux capacitor. Together, they could face challenges in both universes, like stopping Biff from taking over Hill Valley in the Back to the Future world and defeating Death Eaters in the Harry Potter world.
Chapter 653, "Everyone's Champion", is the clearest early answer because it turns Wilderness Survival's situation into a concrete plot event. It opens with As dawn broke, "Wilderness Survival 30 Days" released a notice on...
Chapter 453, "Secretly in Love with Jiang Yan", is the clearest early answer because the hidden truth stops feeling like mere subtext. Early on, On the cruise ship, Zheng Xun walked over with a mournful expression....
Chapter 471, "This is What Happens When You Abandon Sister Li!", is the clearest early answer because it turns Shining Transformation Trip's situation into a concrete plot event.
Chapter 621, "What Makes You Think I Would Save You?", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. It opens with The two walked for a long time before they reached a point where the...
Chapter 588, "Looking like this, he must be a male model in a bar!", is the clearest early answer because it turns Sister Li's situation into a concrete plot event. Early on, However, what they didn't expect was that Zhao Lang had actually....
Chapter 489, "Has She Been Morally Kidnapped?", is the clearest early answer because it turns Guan Xiong's situation into a concrete plot event. It opens with Yeah," Nina nodded, "I thought you looked pretty imposing, must be... and closes on However, Nina wasn't willing to give up just yet;
Chapter 942, "In Which Year Did the River Moon First Shine on People [Extra · River Moon Edition]", is the clearest early answer because it turns Shu Yue's situation into a concrete plot event. It opens with She never expected Jiang Yan meant this. and closes on That was definitely not a dream!.
Chapter 509, "Don't Cry Funeral Until Someone Dies", 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 Because of the commotion from the night before, Jiang Li had...
Chapter 880, "Your sister has been taken to the station!", is the clearest early answer because it turns Lin Jingshan's situation into a concrete plot event. The chapter turns that into something concrete by moving from Simply wearing it already helps dissolve part of the misfortune.
Chapter 605, "The Plan to Surround and Annihilate Team Q Commences!", is the clearest early answer because it turns Shang Shaojing's situation into a concrete plot event.