"That was close" the goblin thought as he swept the sweat off his wrinkly forehead, and after catching his breath for a couple of seconds, he grabbed the pouch and ran towards the hole in the wall hidden behind a desk, and barely pushed himself through.
After a short struggle in the tight tunnel, he popped like a cork on the other side and rolled down a long dark tunnel that led to a small underground chamber that was just beside the basement.
It was very dark and moist and it smelled of onions and mold, and in the middle of the underground chamber there was a Goblin Hoard.
A large pile of spoons, polished glass shards, lost keys, nails, copper coins and other shiny things.
And beside the hoard, there was a small pile of wool socks that the goblin used as a bed, each one different than the other, because goblins never steal two of the same socks.
The goblin opened a freshly stolen pouch and added the copper coins to the pile one by one, throwing them on the pile and listening to them as they clinked.
But his joy was quickly interrupted when he grabbed a single silver coin from the bottom of a small linen sack.
"It burns!" His goblin voice screamed, as the silver coin sizzled with the touch of his skin like a drop of water on a hot stove, and the goblin quickly pushed the sack aside, and the silver coin, still hot from what just happened, rolled outside of a sack and straight into the bits of dry hay, and as soon as it touched the hay, it started smoking.
"Nonono!" The goblin panicked and blew at the small flames that formed to extinguish them, but he only made it worse and they quickly formed into a slightly larger flame, and as the goblin panicked and ran in circles with his long ears dancing behind him, from the flame an extremely thin humanoid a couple of times larger than the goblin suddenly rushed out and started growing, while the frightened goblin dashed and hid in the pile of socks.
It appeared to be made out of coal or burnt wood, and it quickly reached the height of a shorter human, but it's limbs and body were barely thicker than the branches.
"I told you not to awake the master!"
A deep voice shouted.
"Rilly?" The goblin asked with a surprise.
"Perhaps I should burn this nest to teach you a lesson!"
The abyssal voice answered
"No! Take the coin! Leave my lair alone!"
The goblin begged and covered his face with his ears.
"I have no need for coins!" The pitch-black creature yelled and a tongue of flame jumped out of it's mouth and burned the few hairs on top of the goblin's head.
But while the goblin trembled inside his lair, a light appeared on the horizon in the east, a break of dawn under Nogrly, the Morning Star.
And as the sun rose from the horizon, the dark creature quickly shrank and morphed back into a feeble brownie.
"Rillyyy!" The goblin screamed furiously with his teeth clenched.
"W-what happened?" the frightened brownie replied.
"You turned into a boggart!"
The goblin screamed,
"A boggart!"
And the goblin wasn't wrong, Rilly indeed did become a boggart, as brownies usually do when enraged or mistreated.
"We are fortunate that you didn't burn the master's house, as boggarts usually do!"
The green creature shouted and pointed his long clawed finger towards Rilly, who curled in a corner.
"Now to redeem yourself, take that silver coin from my hoard and carry it back to the master!"
"Y-yes! You are v-very kind! Thank you!" Rilly replied.
And with his head tilted, he slowly walked into the bit of ash with a coin in his hands and disappeared, quickly reappearing in the fireplace, and before the peasant could get up, Rilly placed a coin on the table and went back into the ash and vanished until next night when he could serve again. 

Meanwhile, the goblin laughed and rolled excitedly on his clinking hoard, happy how he fooled the peasant and the brownie, he tossed the coins around in his lair and celebrated his cunning, cheerful about his victory until his greedy impulse to expand his hoard brings him to the surface once again.