(A/N) Okay, this is my first vocaloid fan fiction. It's based on the song "Trick and Treat" (hence the title) which I really like. The parts in bold are the song, so enjoy! By the way, if you want to see Miku, Rin, or Len's outfit, it's this:

( youtube .com/watch?v=insCeDwbPaI )

Oh! This is Alternate Universe. :D

Once upon a time, not too long ago, was a town. Not too big, and not too small. It was easy to overlook this small town, since it was so innocent and boring. However, each town has a secret, and this town was no different. In fact, their secret was far more frightening than others, for there was a forest behind that town that no one dared enter. Every time someone did enter, they were never seen again. Not one. When someone went missing, it wasn't thought about what happened. It was obvious. Some daring person decided to venture in.

The disappearances were ignored, and no one talked about them. It was as simple as that. Only the foolish would walk in. They'd ignore the heeds of danger, and no one ever thought about what would happen next. Just another tally on the long growing list of disappearances. No one ever hoped for them to come back, since it wouldn't happen. Not today, nor tomorrow, or any other day.

However, it was when outsiders came that things would spice up. The clueless fools would think that the forest was a simple superstition and go in. Yet again, no one reappeared. Things overlooked by the small, seemingly innocent town. The residents no longer cared. It was just another thing to overlook. Nevertheless, a new stranger had appeared….

The foreigner's big eyes shined with a clear, blue tone. Her teal, waist length hair was tied into two simple ponytails on each side of her head. She had an innocent look about her, and somewhat naïve. She grinned at the townspeople throughout the city, a small hop to her step as she walked around. She wore a long sleeved, black dress, a contrast to her sparkling personality. The townspeople would smile back, thinking about how long it will be until the girl disappears.

Two figures stand, hidden in the shadows of the alleys. Both look no older than perhaps fourteen, yet their burning green eyes make them seem increasingly older. They were both twins, and kept the resemblance. Both wore matching outfits, oddly seeming like they belong in the clothes of a doll. Although black, the stripes of red made the outfits give off a sadistic look instead of a playful one. Their eyes had a chilling look in them as they watched the girl walking through the town.

"So a new stranger has arrived." The boy twin stated in interest.

"Quite. Another 'addition' to the collection." The girl twin snickered malevolently.

"Think she'll be easy to trick?"

"She seems immature enough to fall into any trap."

"So, shall we do the usual?"

"Naturally."

Both twins giggled excitedly, as they blended into the shadows of the alley until they both disappeared. A small giggled echoed off the walls of the alleyway and spread into the city. The young stranger turned around curiously; suddenly getting the feeling she was being watched. She froze, before continuing her skipping through the town. She found it abnormal to hear two children giggling so oddly, yet she ignored the feeling of paranoia filling her.

Come deeper; come deeper into the forest where you heard a voice so kind.

Come on in, come on in, you never know who in the forest you will find.

That feeling of being watched stayed with her the whole day, as well as she couldn't sleep well. The stranger rubbed her eyes tiredly, and yawned. It was becoming night yet again, and she was hoping to sleep well tonight. She glanced up to the moon, noting that it was a full moon. She smiled and continued walking until she reached the edge of the town, which was where the inn she stayed at was. As she dragged her feet towards the inn, she heard a voice of a child, one which sounded gentle and quiet. "Hey Miss, where are you going?"

The woman looked around, trying to look for the person speaking to her. "To the inn. I'm staying there." She replied, still unsure where the voice was coming from. "Oh." The voice sounded disappointed as it let out a sigh. "I was hoping you could play with me." The voice whispered softly, as if embarrassed to ask the question. The stranger smiled, as she realized the voice was coming from the forest. "Sure, I guess I could come for a while…" She heard the child giggle in excitement. "Yay! Then come on! Try and catch me!" Rustling in the bushes hinted where the child was, and the girl found herself following the child.

Although the stranger found it odd to see a child playing all alone in the forest in the dark, she followed the boy, walking and listening for him. An odd rustle behind her alerted her of someone's presence, and she quickly turned around. She jumped towards the bush, and was able to grab the wrist of a child. "Caught you!" the stranger chuckled. She then looked at the child again, and realized it was a girl, -who seemed quite smug- that was hiding in the bushes. She immediately let go, and muttered a small sorry.

Behind the woman, she heard an innocent laugh, and turned to see the boy whom she had heard near the inn. "Got you! You caught my sister, not me!" he stuck his tongue out in a mocking gesture and walked over. It was then that the woman noticed the resemblance. They were twins. "You didn't tell me you had a twin." The woman defended her failure to catch the boy. The boy twin nodded. "Yeah, you're right. Then come on, let's play another game! But to play it, you need to keep up with us!" he alerted her. She nodded and smiled. "Agreed. Now before we play, what are your names?" she asked curiously. The twins laughed in unison. "Keep up with us, and we'll tell you." They said together. The woman shrugged. "Very well. But my name is Miku. And I'm glad we're playing. This is so much fun!" Miku grinned and stood up. The twins giggled and looked Miku. "Wait, it'll get even more fun." The girl twin giggled in delight. Miku was confused, but nodded. "Okay then, let's play!"

Unless you haven't heard the song, it's obvious who dies. -_-; This is going to be three chapters long, I believe, and I'm going to have fun with this! MWAHAHA! *ahem* Sorry 'bout that!