Mr. Ice looked at both of them with a serious expression.

"Writing a story with two authors is completely different from writing alone," he began. "A single author can create anything without restrictions. But with multiple authors, you must follow certain rules—causality, effect, and even the butterfly effect. You can't randomly introduce characters or powers without considering their impact on the world. Otherwise, the story world will lose its balance."

Tom raised his hand. "Then how are we supposed to write the same story together?"

"You must create a Book of Causality in every story," Mr. Ice explained. "In this book, you will record every cause and effect of the elements you introduce. If something doesn't follow the rules written in the book, you won't be able to write it. Your pens won't allow it. And if you want to introduce something major, you must first edit the Book of Causality before writing it."

Tom sighed.This is already giving me a headache…

"But," he continued, "if only one pen is allowed in the dreamspace, how are we supposed to write together?"

Mr. Ice pointed at the pens. "If you want to write the story together, you each need to pick your own pen and write separately at first. When you want both stories to merge into one world, you must define everything clearly—world name, country names, and even the other main character. You must also define that character's basic traits and powers. Once both sides match, your stories will merge, and the Book of Causality will appear."

Emilia nodded slowly. "Okay… that makes sense."

Tom rubbed his forehead again. "Fine. But how do we contact you again?"

Mr. Ice answered casually, "Go order seventy-seven vanilla ice creams."

Tom blinked. "…What?"

"You heard me," Mr. Ice said. "In this world, I'm writing myself as an ice-cream vendor. Go to Bakinson Ice Cream Shop, ask for the man named Peter, and tell him you want seventy-seven vanilla ice creams. I'll know you want to meet me."

Tom stared at him, speechless.Why does everything have to be this weird…

Mr. Ice raised an eyebrow. "Any more questions?"

Both Tom and Emilia shook their heads.

In the next moment, Tom and Emilia were teleported back to her room.

Mr. Ice watched them disappear and sighed deeply.

"What kind of dumbasses are these two…" he muttered to himself. "They used time travel with their pens, yet they didn't think to ask the pen how to co-write a story. And the higher-ups still have hopes for them… We couldn't give them exceptional IQ or they would attract too much attention, but still…"

The scene shifted to Emilia's room.

Tom and Emilia looked at each other and decided to meet in the dreamspace at night. Even if only one pen could enter at a time, they could at least discuss and start building their Book of Causality and Effect together.