(The Mystery Shack, Mabel and Dipper's Bedroom; 9:00 pm)
The twins were sleeping peacefully in their beds, Dipper firmly grasping his "3" book while Mabel was hugging her pet pig, Waddles, and muttering something about marshmallows and smile dip. The room looked the same as always: an average attic bedroom, with a dresser near the door.
Sadly the peace didn't last long, as a loud bang was heard, waking up both twins and startling Waddles in response, who went running off to a corner. The twins got off their beds and walked to the window, seeing outside at the sky a round, green portal had opened, with a pair of mysterious figures coming out of it before it blinked out of existence.
"Did you see that too, Dipper?" asked Mabel, turning to her brother.
"Yes, Mabel, I did." answered Dipper as he walked to the dresser, went inside and then came out with an armor made of teddy bears and two golfing clubs, one which he handed to his sister. "And you can bet we're gonna do something about it."
(Outside the Shack)
After somehow getting out of the shack without waking their uncle up, Dipper and Mabel sneaked up until they hid behind some bushes close to the place the mysterious figures had fallen in.
Wanting to make sure if they looked threatening, Dipper took a peek of the creatures, one which looked like a tall, muscular man and another which was smaller and thinner. Dipper immediately decided they were dangerous enough, and hid back to the bush.
"Okay, Mabel, this is what we're going to do: we sneak behind them, hit them with the golfing clubs and flee as fast as we can while screaming like little girls if that doesn't work." instructed Dipper, glancing between his weapon and his sister. "Are you ready?"
"More ready than ever!" the girl was shushed by her brother, who gave her an angry glare as he slowly released her mouth. She started to talk in a whispering tone afterwards. "Sorry, more ready than ever."
Nodding in unison, the twins jumped out of the bushes and screamed as they went running to the figures, hitting them once with their golf clubs once they were close enough, and then running back to the bushes while screaming afterwards. Once they relaxed and checkedtheir weapons, they both had been deformed with a pair of particular shapes: Dipper's had a long neck deformation, while Mabel's was more like a huge spoon.
Peeking back again to see the figures, they were now revealed to be an animal-likelight blue alien with a pink crest and reins and saddles, and a smaller alien covered in orange fur and wearing light blue shoes and a big green hat with a belt with a star. Nearby them were a pair of clothing, one slender black full bodysuit with a thunder helmet and a large hood with the upper part in red and the under part in black, with a pair of thunder like thing on the top.
With looks of pure confusion, the twins got out of the bushes and walked to the duo, who briefly looked around before turning to the twins. "See, Sylvia? I told you we would manage to get here with a single portal!" told the orange alien to his light blue companion, Sylvia.
"So, you were the figures who came from the portal?" asked Dipper.
"Yep." answered the orange alien.
"But your shadows looked much more different from what your appearance would suggest!" exclaimed Mabel.
"Oh right, portals have a temporary effects on shadows, so they sometimes seem different before the real persons are revealed." explained the orange alien.
"I don't think I should take that as a valid answer." replied Dipper.
"Then try this: we accidentally grabbed some spare clothing from some other aliens before we went through the portal and forgot to change until we got here." sarcastically suggested Sylvia.
"That sounds more logical." the alien pinched the bridge of her nose in response as the boy continued. "Anyway, who are you two?"
"I'm Sylvia, and this little furball over here is my best friend and partner, Wander." explained Sylvia, patting the orange alien, Wander, on the head as she did.
"I'm Dipper and this is my sister, Mabel." introduced Dipper, Mabel waving hello as he finished. "So, why did you come here?"
"We came here because "The Holiday" has arrived, and we were thinking we could go through other universes to deliver gifts, instead of just our own."
"The Holiday? You mean christmas?" asked Dipper.
"What is this thing you call "christmas"? We simply go around the universe, and some others, delivering gifts to people we have met over the past season." Wander paused for a moment before finishing. "Of our lives!"
"I knew it, Santa Claus and his reindeers are aliens!" exclaimed Mabel in excitement.
"No, Mabel, these are aliens from another universe, who are doing something related to christmas, but which is not actually the same holiday. At least, that's what I get." explained Dipper to his sister before turning to Wander and Sylvia. "So, what are you going to do here?"
"We will deliver gits to everybody in this city before you can say gifts forever!" exclaimed Wander in excitement. "And we would like you to help us with the last detail for our gifts!"
Wander handed the twins a pair of gift boxes, and they looked at the gift tags, which read "For Dipper" and "For Mabel" in red letters on a white background, and then they turned it around see "From _" in white letters on a red background.
"Why is the back part missing the name someone?" asked Dipper, turning to Wander with a raised eyebrow.
"That is where we need your help, you'll tell us the name of one person who could benefit from the attention and good deeds these gifts will bring, and we'll mark his name in it so that the people believe he did it!" explained Wander as he got on Sylvia's back.
"The person has to be naturally grumpy, doesn't do good things on average and would like people to be good or competent for once." added Sylvia. "Do you know anybody that would fit that description?"
"Hmm, I think we know just the person." answered Dipper and Mabel in unison.
The twins whispered the name in Wander's ear, and he smiled widely before marking the back of the gifts with the name, he and Sylvia suddenly being grabbed by a comet passing by in front of the twins' eyes. Exchanging shocked looks, the twins went running to the tallest hill so they could see the city, also spotting Wander and Sylvia inside the comet, Wander waving hello as they approached the city.
Once over above the city, Wander took out his hat and waved it, somehow making hundreds of gifts fly from it and fall to the streets. The first ones to get their gifts were Candy and Grenda, turning to the back to see it was reading "from Stan Pines" now. They exchanged worried looks after reading that, but still opened their gifts, screaming in joy once they saw what they were: a voice modifier for Grenda and a pair of gloves with fork claws for Candy.
Some more gifts started to land at random on the city: on chimneys, on ponds, and on houses, but they all came out intact in the end. Pacifica, Robbie and some other people walked to the gifts and grabbed them, only turning the tag once, reading it quickly, laughing in disbelieve and then opening their gifts, also getting filled with joy once they saw what they got.
Once everybody had their gifts, the folks of Gravity Falls all celebrated and shouted in unison, Wander and Sylvia exchanged pleased looks as the comet went to the hill the twins were at, and once there, the twins move away so Sylvia and Wander could come out and land near them, Wander exchanging a high-five with Mabel while Dipper exchanged it with Sylvia, the quartet looking back at the joy-filled city.
"And that's how you deliver gifts, Wander Over Yonder style!" exclaimed Sylvia.
"Grunkle Stan is gonna be so happy once everybody is thanking him for the gifts he delivered." remarked Dipper, laughing a bit before finishing. "And we'll also get a pretty good laugh while we see that happening, haha."
"Thanks for the gifts, Wander." thanked Mabel as she hugged the orange alien, who then released himself off her grasp to hug Dipper. "Oh right, Dipper is also grateful for the gifts."
"I love to help, so I was more than happy to do it. Sylvia was also glad that she could help." stated Wander, the portal opening behind him and Sylvia shortly after that. "Goodbye, Dipper and Mabel! I hope we see each other next year! And remember: never hurts to help!"
The aliens waved goodbye before going to the portal, the twins waving goodbye as they went inside. Once the aliens had gone through the portal, it blinked out of existence, with the twins sighing before walking back to the shack. On their way there, they accidentally stepped on something, looking down to see a pair of letters with the words "invitation" big red font. "Are these supposed to be invitations?" asked Dipper as he and his sister grabbed the letters and opened them.
They took out the note inside and they both shouted "No way!" in excitement before they went running towards the shack, jumping in excitement along the way.
The End