This one's a bit longer than the last chapter. I'll be working out a schedule for my stories soon. But for now, have this chapter and another afterwards. Enjoy!
Mabel's POV
"First off, your Grandpa Stanley is not dead. As you've probably already figured out. So, around thirty-five years ago he started writing those journals. One of the projects he was working on was... A dream demon named Bill Cipher." Dipper and I gasped at the mention of Bill. Stan glanced nervously at us. "What, you've met him?" Dipper nodded grimly. "We've had a few experiences with Bill." Stan cast another worried glance at us before continuing. "Anyway, this was one of the few projects I helped Lee here on. We summoned him, but when we did we thought he was just a being to do someone's bidding with no questions. He was all knowing, we could ask him anything and he would tell us. But what we didn't know was that Bill was a blood-thirsty creature with the desire to rule the universe. Fiddleford, Lee's colleague, figured out that Bill was up to no good. He reported to us, and the three of us built a portal to banish Bill. But as it turns out, we couldn't complete the banishment, because the prophecy-" Dipper raised his hand. Stan stuck his own hand out. "Wait. The prophecy hadn't been fulfilled yet. The Portal was getting feistier, and it requires someone to go through in order to prevent it from destroying the universe. We argued endlessly, and Stanley volunteered to go through. Of course I was against it, but my brother pushed it aside and gave each of us a journal to hide. I got Journal One, Fiddleford got Journal Two, and Lee got Journal Three. We all hid a Journal, and then when we got back, Bill was waiting for us. He made Stanley go into the Portal, and Fiddleford left, traumatized. I made Bill go back by saying a "temporary banishment" incantation. Bill could only be brought into this world if someone summoned him. I figured the best way to prevent that was to find the Journal I hid. Unfortunately, based on what you guys are telling me, it sounds like someone found Journal Two, since Dipper here found Journal Three. Who was it?" I rubbed my arm nervously. "Gideon found it and made a deal with Bill so he could enter your mind and steal the code to your safe."
"Is that how he got in?" Stan asked. I shook my head. "We stopped him before he could do it." Stanley's eyes widened. "WHAT?! Someone has summoned Bill Cipher?! This is worse than I imagined! Children, how exactly did you defeat him, and what did he say?"
"We didn't really defeat him, we just started to and then he kinda just surrendered. We were in Stan's mindscape and we imagined a portal out of Stan's mind. Before we could do it, he stopped it, and he said something like he was impressed with us and we were more clever then we look, and we might "come in handy later". Then he said a day would come in the future when everything we care about will change. Then he said he'll be watching us and he disappeared in this weird circle thing," I explained. Stanley closed his eyes in regret. "This will not end well."