Thomas was a young, small, rather and unfortunate son. The poor child was vagrant, causing him to be quite impecunious and stricken by poverty.
Crawling out of the small shelter he had erected, Thomas had noticed that this year's season of fun, enjoyment, candy, and costumes was finally upon the world. He was never really one for the famous night, as he never really had the chance to dress up, or rather do anything pertaining to it. He was either too young and had nobody to go with, or didn't have any sort of costume to put himself in. But this year he figured he was at the perfect moment in time to partake in the event.
--
It was the day of Halloween, and Thomas didn't actually have anything to dress himself up with, and was too indigent to actually buy himself somethingSo using different parts and items that he had found, Thomas had fashioned his very own costume to wear. He decided to go as a knight, since it would be the easiest thing he could make, and he really loved them. Since he was limited part-wise his costume wasn't complete, but he had managed to make it work.
His costume had consisted of: A majestic knight helmet made from an old pot and a bent grate he had found near a dumpster, a shoulder pad made from a large tin can, a bracelet made of aluminum, and another made of cloth, and finally his knight's cape, which was made out of a bedsheet he had slept with.
--
Well, the sun had painted the sky in an evening tone, and it was time for children and their parents to head out and trick or treat. After seeing a few people in a nearby neighborhood, he had decided to grab a plastic bag and head on out. He saw a small group of children that looked to be his age, so he went to see if he could perhaps tag along or stay with the group.
Turns out they were a bunch of snobby jerks and they started mocking him and making fun of his costume, god, these people.

"Hey, cut it out" called out a a deep voice, appearing to be a large man and his children, who were trick or treating. The evil children scurried away into the darkness where they had come from. Shortly after, Thomas explained his costume and his situation to the small family. "Come on, you can tag along with us" Said one of the boys, with his family agreeing.
This had finally given him a sense of enjoyment, and a great feeling of bliss.

-end-
TL;DR: Poor homeless child makes a costume out of different parts, goes out and halloweens, ending.