Dipper's POV
One day I was just reading out of my journal. Mabel went downstairs to the kitchen, and before she was able to get back, I saw a really small white figure which looked familiar, and another I didn't recognize. But before I could get a good look at them, I was tossed into a sack. Then I heard a girl say, "We got the Pines boy, brother. Next is the girl."
About an hour later, I was in a familiar room. Gideon's room. I saw Gideon and a strange girl. "So, Dipper Pines. My brother's told me about you." that girl taunted. I looked confused. "Brother? Someone actually goes through the pain of being Gideon's sibling?" I asked her. She glared at me. "Gideon's not usually annoying, genius. Anyways, I am Luna Bellatrix Gleeful. I'm 11 years old. When we're done with you, we'll have your poor little excuse of a sister and your great-uncle hostage with you. Then finally Gideon will get his wish. To rule the Mystery Shack with your sister as his queen." Luna said, in a Southern accent not unlike her brother's. She looked like a giant next to Gideon. Luna had chestnut brown hair, hazel eyes, dimples, a purple shirt, a cyan skirt that went to her knees, knee-high rainbow striped socks, and black loafers. She looked innocent, but had a wicked smile. I knew that Luna couldn't be different from Gideon, except for the fact that he made her look like Hagrid from Harry Potter and they didn't look related. "So, where's your journals?" Gideon asked. He thought I had journals 1 & 3, when I clearly only had the 3rd one. "How many times do I have to tell you, I don't have it? And how did you get out of prison?" I asked. Luna smirked. "I got him out of there. I was hiding from the police in Atlanta, Georgia. They found out I stole their walkie talkies. But one day I found out that Gideon got in prison, because of your stupid uncle. He sent an urgent message in the Atbash cipher, so I flew back to Gravity Falls and freed him when those dumb cops weren't looking." Luna explained proudly. I couldn't take this. Gideon has a sister crazier than him, and they were planning to kidnap Mabel & Grunkle Stan, maybe even Wendy and Soos!
Luna's POV
I just met that Pines boy, Dipper. He's pathetic. I want to call him a little boy, but he's a year older than me. Now me and Gideon were going to hold Mabel and Stanford Pines hostage and take over the Mystery Shack. When we first came into Gravity Falls, we met Stanford. This was before the Pines twins came for the summer. I was 7 and he was 5 at the time. Stanford knew we were trouble, which our parents were too blind to see. He was annoying, and our family, I mainly mean me & Gideon, formed a rivalry with him. We vowed to destroy him and steal the Mystery Shack. There's a possibility he has the first journal. When Gideon became known as the lovable physic child, Mom told me to hide in the basement so Gideon could pursue his career. Then Mabel came. She broke Gideon's heart. And now my goal is to make sure she regrets it and apologizes lying in a hospital bed. Anyways, after we kidnapped Dipper, Gideon put the boy back in the sack. We headed to the Shack and found Dipper's extremely poor excuse of a twin. She was knitting, tears rolling down her face. "Dipper, where are you?" Mabel muttered. I had another sack, and put her in it. "WHAT THE HECK? YOU BETTER GET ME THE HECK OUT OF THIS FREAKING SACK, OR I WILL UNLEASH THE GNOMES ON YOU!" she screamed. When Gideon & I took her back to our house, she strapped her to the wall.
Mabel's POV
Gideon & his sister, Luna Bellatrix Gleeful, kidnapped me and Dipper. Good thing I found him. Luna Bellatrix (I prefer calling her Luna Bellatrix, it sounds better) is just as crazy as Gideon. After they held me hostage, Luna Bellatrix said, "Mabel & Dipper Pines, either you give Gideon the journal, or he gives you an Lose Memory Potion. We made it ourselves. It works. So, which one? Lose the journal or your memories?" We just paused. Luna Bellatrix held our mouths open, and Gideon poured something in my mouth. Then everything went blurry. I thought, who am I? Oh, wait, I'm Mabel Pines. I've lived in Gravity Falls since I was 2, with a very nice twin brother, Dipper. I loved him dearly, but he got in the way of me & Gideon. We were happily dating until he broke us up. Dipper strapped me to my bed and wouldn't even let me go to the bathroom one night. And my whole family prevented me from dating Gideon. And his family, too. I don't care anymore. Nothing stands in the way of true love, not even my twin brother. Me & Gideon will live happily, rule Gravity Falls, and show Dipper not to interfere with my life.
I really just loved Lil ol Gravity Falls' story It Runs in the Family, so I wanted to do something like that. I'm not trying to rip off the story, it's just one of the best ones I've ever read, and it inspired me. So don't complain. If you want to, don't whine about it. Except in this story, BOTH Mabel & Dipper forget themselves.