Who gains posession of the book?

Sokka

(Hey, this update took a while. Sorry about that.)

Sokka managed to pull the book out of her hands and quickly began writing in it. He made a section titled Team Avatar and quickly wrote again.

New Rule: Nobody on team Avatar can take this book without Sokka's permission.

He saw Katara try to grab the book once more before she felt her hands freeze in place. "Seriously Sokka?" she asked annoyed. She sighed and sat back. "Why not just make a rule that only you know about the book at that point?"

"Like you said it's dangerous, and I will need advice on using it right. Heck, I almost made Firebending impossible before I realized how it would mess up stuff for everyone, not just the Fire Nation," Sokka said before closing the book and putting it in his bag, "That said, it found me for a reason, and I want to use it to help however I can."

"So, when are you gonna tell Aang?" she asked.

"Probably tomorrow, he's sleeping right now after all."

"Something tells me you made him sleep with that book," Katara replied with narrowed eyes.

"Oh right, I need to erase that rule now, since I only needed it for the night." He opened the book and erased his rule about Aang. "I know you probably don't fully trust me with the book, but how about I let you propose any rule you want?"

Katara thought for a bit before smiling.

(Comment suggestions for what rule you'd like her to make)