A/N: I don't own Adventure Time or Invader Zim. ON WITH THE STORY!
Brenda's P.O.V.
"Come on," Alexis said quietly. We were only about fifteen yards away from the tree fort, so we had to be quiet.
We hid inside the leaves of the tree fort and went to a window. Brady said, "Now we just have to figure out how to get Alex out of the house."
"That's what I was thinking. How'd you know that?" Alexis asked.
"We can read minds," Brady and I said in unison.
"You guys just keep getting weirder and weirder," Alexis said to herself.
"Hey guys," Marceline said from above us.
"Hey Marcy," Brady and I said in unison.
"Hi Marceline," Alexis said, not taking her eyes off the window that showed her brother to us.
"Hi," Shadow said, staring at Alex through the window.
"Still evil Alexis?" Marceline asked.
"My body was possessed by the Lich, my soul was locked in a jar, and I had no control of what the Lich did while he was in my body," Alexis said.
Alexis smirked and said, "Alex just walked out of the room. Alex is not on the floor anymore."
She unlatched the window and stepped through it. "Come on," She said, "It's safe!"
Shadow walked in after her, walking into the darkness so no one could see her. I saw Alex walking back up the stairs. He had a large red sword in his hand. "Alexis! Look out!" Brady and I cried.
Alex grabbed Alexis before she could even turn around. "No! No!" She exclaimed, "Let go of me Alex!"
"Alex isn't here anymore," The Lich said, "I'm the Lich." He spun her around and pushed her against the wall. The Lich slit her throat with Finn's demon blood sword. The Lich let go of her, and she grabbed her neck.
She fell to her knees, trying to keep herself from bleeding out. Shadow quickly tried to make her tentacles wrap around Alex, but he was too quick, he ran out of the room, and ran out of the tree fort. Shadow retracted her tentacles back into her back, she stepped into the light and ran over to Alexis. "Are you okay?" She asked.
"Later guys," Marceline said awkwardly. She flew away with her umbrella shading her from the sunlight.
Brady and I ran into the tree fort and to Alexis. "Yeah Shadow. I'm okay," She said, coughing, "It's just a scratch." She removed her hand from her throat and Brady and I saw the slit was already healing.
She coughed again and got to her feet. "I'll be fine," Alexis said, "Now, we need to find out where 'Alex'," She put air quotes over Alex, indicating he was possessed by the Lich, "Went before he breaks that vile. It only works at the highest point on the planet. Now where is that?"
Brady and I looked at each other and we said in unison, "The Ice King and Ice Queen's castle."
Nobody's P.O.V.
The Lich climbed the frozen ice castle to the highest point of Ooo with Alex's soul in a cursed jar that was in his pocket. "You'll never get away with this!" Alex yelled, hitting his fists against the glass, "My friends will stop you, and you'll be sorry!"
The Lich chuckled at the irken. "I will get away with this. When I smash this vile your sister's stupid scientists gave me, all species in Ooo will DIE!" The Lich exclaimed.
"I hope my friends get here in time," Alex said, crossing his fingers.
Meanwhile, Alexis, Brady, Brenda, Fionna, Finn, Cake, and Jake were all rushing to the ice kingdom. "Come on Cake!" Shadow exclaimed, "Can't you go faster?"
"I'm sorry! I'm going as fast as I can!" Cake exclaimed, defending herself.
"No worries. Once the sky turns dark green, we have half an hour to keep breathing in the air before it turns deadly. Once the sky turns dark red, people will start to die, and THAT'S WHEN WE CAN START TO WORRY!" Alexis exclaimed.
The Lich threw the blue vile to the ground, and it smashed into the ground. The sky turned dark green.
"Faster Cake!" Shadow exclaimed.
"I'll get there before you guys!" Alexis exclaimed. She jumped of Jake and six long metal spider arms extended from her PAK. They hoisted her into the air, and she dashed to the ice castle.
Alexis got to the top of the ice castle and saw her possessed brother laughing evilly. "Let my brother go!" Alexis shouted, clenching her fists.
"No! And now, you, and the rest of the people and animals on this planet will die!" The Lich exclaimed, laughing evilly again.
Alexis growled and charged at the Lich. Her metal spider legs had retreated back into her PAK and she started to beat up the Lich. "Why you rotten brat!" The Lich exclaimed.
He punched her clear in the spot where her nose was supposed to be. She fell to the ground, and the Lich put a foot on her spine and started to smirk.
"Is there no one else?" The Lich exclaimed, laughing.
"Yeah!" Brenda exclaimed, "Us!"
Finn and Fionna grabbed their demon blood swords and Shadow started to do an incantation. A spell. The Lich started to come out of Alex's body. "What? What's happening?!" He exclaimed.
"Godin maar warn zula ma rah!" Shadow exclaimed. The Lich went all the way out of Alex's body.
"What was that you mangy rat?!" The Lich exclaimed angrily.
Shadow said, "I put a spell on you. Now you can't reenter his body." She smirked and said, "Or anyone else's. That spell was for you and your possessing power. You can't go into anyone's body anymore. It doesn't work."
The Lich tried possessing Alex's body again, but he couldn't get inside his body. "No!" The Lich exclaimed.
"Good!" Finn and Fionna exclaimed, "Now we can stop the Lich once and for all!"
Finn, Fionna, Brady, Brenda, Cake, and Jake quickly beat up the Lich. "Good," Brenda said.
"He's defeated," Brady said.
"Alexis!" Finn exclaimed.
"Stop Formula X!" Fionna exclaimed.
Alexis nodded and got the vile with the green liquid in it and the spray gun out of her PAK just as the sky started to change to dark red. Alexis quickly poured the liquid into the spray gun and she said, "This spray gun will turn the liquid into a gas, and when I squirt it out, it'll have a counter effect against Formula X! I call it the thing that saves all our butts!"
Alexis squirted the now gas into the air, and the dark red sky started to change back to its light blue color. Shadow smiled and said, "Now that's covered, anyone know how to trap this guy?" She was referring to the Lich.
"Freeze him in amber," Finn and Fionna said in unison.
"That's the only way to stop the Lich," Jake and Cake said in unison.
Shadow nodded and said, "I know the perfect tree." She picked up The Lich, who was unconscious, and carried him out of the ice kingdom, to her favorite tree. There, she encased him in amber and went back to her cave.
"From that day on," An old woman said, "Ooo was in much piece. The Lich was encased in amber forever."
"Grandma," A little girl with cat ears said, "How do you know this?"
"She was there dummy!" A little body with sharp teeth and a black tail said.
"Now Ryder, don't talk to your sister like that," The old woman said.
"Sorry Grandmother," Terry said.
"It's fine dear. Now Beth, do you now know why you shouldn't play around that old tree?" The old woman asked.
Beth nodded and said, "Yes Grandma Brenda."
"Good," Brenda said, "Now go clean up. Alexis and her brother are coming."
"Are here, actually," Alexis said, chuckling. She was still twenty one, thanks to the immortality potion. Alex on the other hand only aged five years, so he was almost twenty-six.
"Telling your grand-kids the story?" Alex asked.
"Yeah," Brenda said.
"I still can't believe you and Brady are sixty-five," Alexis said, smiling.
"I still can't believe Finn and Fionna married and Marceline and Marshall Lee," Alex said, rolling his eyes.
"I can't believe Grandpa died," Beth said, looking down.
"Now sweetie," Brenda said, "It's okay. We still have Brady and his family."
"Yep," Beth said, "And that'll never change."
Brenda nodded and said, "Never. Anyway, Alexis, how are you and Russell doing?"
"We're doing just fine. Reba's doing great, by the way," Alexis said smiling, referring to her part skeleton, part ragdoll, part irken daughter.
"Good," Brenda said.
"Grandma, you tell us another story?" Beth asked.
"Sure Beth," Brenda said, "One time, when Brady and I turned sixteen..."
A/N: The End! Yay! I finally got this story done after lots of hard work! Thanks for reading! Review! Bye!
-Nicky
:)