Escape From the Tunnels

One day, or even night, everything was unusually dark. Only the quiet sound of the rain was able to be heard from miles.
In one dark room, there was a unicorn mare, laying there on the ground, sleeping. She had silver white coat and purple mane with pink tips. It was of course, no other pony than Sweetie Belle.
The mare suddenly woke up in shock. She looked around, but it was too dark.
"It's too dark," Sweetie Belle thought. "how am i gonna.." She stopped thinking about the darkness in the room, when she realized that she can just use the magic from her horn. "Oh, of course, i forgot about my horn."
She closed her eyes again and focused. Then a light-green light came from the tip of her silver-white horn down to the bottom of it. The bright green light shone across the dark room.

Then Sweetie opened her eyes, quite reliefed from the lack of darkness. But then she noticed the iron collar, placed on her neck and tied to a metal pole.
"Oh no.. No no.." The mare's pupils got smaller from the sudden fear that slowly took over her body. "What is all that?! Where am i?! How.. how did i ever got here?" Sweetie Belle looked around, searching for a door, a window or a crack on one of the four walls where she could possibly escape. But there was none of the first three options, except for a door, located right behind her.
"Oh, thank the princesses, there's a door. But, this leash.." Sweetie looked at the leash connecting the collar to the pole. "Hm. . . " The unicorn mare started thinking again. Until she finally came up with the most obvious solution... Cutting it with magic, of course.

After she cutted off the leash, she was free to roam around the room with no problem. But that collar, it just stood there.. on her neck, untouched and shiny like it's brand new.
Sweetie tried to break it with her magic, but she failed. Either the collar was too tight or it couldn't fit thrue her head to get it off.
Giving up on getting the iron collar off, the mare started walking around the corners of the room out of fear and boredom. Really weird emotional combination, even she herself realized that.
"The door is locked, there's no windows here, and if i give my horn a break, everything will turn dark once again!" Sweetie Belle lowered her head down. She was in a situation where she wasn't sure what the true ending could be.
Then Sweetie looked up, because she thought that there was something, at the right corner of the room, where her magical light wasn't enough to shine up. The young mare got up and walked towards the darker corner.
Suddenly Sweetie stopped and gasped in horror, from the thing she saw there. In the corner of the room, there was a small skeleton of a young pegasus filly, just laying there, curled up. It had a collar too, but obviously smaller and rustier.
"Does that means that i'm not the first one here?" Sweetie asked herself.

"Hey!" Sweetie gasped from fear. "No no! Don't be scared and turn around! I won't hurt you."
Sweetie Belle really had no choice, but to turn around. Then.. her fear suddenly disappeared when she saw another pony behind the locked door. Sweetie gasped from surprise when she saw the teen colt.
"Can you help me?" She asked the stranger colt. "I don't know how i got here or how to get out! Perhaps, you may know the exit..?"
The colt slightly frowned and nodded for 'no'.
"But.. Maybe we can find it together? If you don't mind." The colt asked the unicorn. Both then looked at eachother akwardly.
"I would actually love to! But.. the door is locked and there's no key.." Sweetie Belle tilted her head down.
The colt looked at the sad mare with confusion. Then he started asking her questions.
"Okay, but aren't you supposed to use the magic from your horn to escape from your room? Just askin'." From that question Sweetie Belle's ears twitched in surprise. "Seriously? Don't tell me that you didn't try blasting the door out!"
The silver-white mare sat on the dirty ground and facehooved herself.
"DARN IT!!" She yelled. After that, she stood up and started walking backwards. Then she stopped at curtain point, only to warn the colt. "WATCH OUT!! I'm going to blast this door!"

Then Sweetie's green eyes closed once again. The light from her horn stopped glowing, to give herself more focus to make a ball of energy, ready to be blasted at the locked door.
"Hgh, come ON!" Sweetie Belle yelled to herself.
Then the light from her horn came up again, but it was stronger that the previous. The room started to get hotter from the ball of energy, forming on the tip of the mare's horn.
Then it's size increased more and more, until it flew away in a high speed from her horn, right at the door. It was completely destroyed, even a little bit of the walls.
Sweetie Belle was finally free from that cell.

"Hey!" The colt ran inside the cell, where the now tired mare was. She was breathing heavily and shaking. "In the name of Luna, are you okay, miss?!"
Sweetie looked at the colt, then fell on the ground, tired.
"Heheh, yeah, i'm okay! Thank you, it's just that it's my first time creating a blast to desrtoy something." Sweetie Belle smiled, when everything went dark again. "I need to give my horn a break, or i'm gonna break it without me noticing!" Then they both giggled and laughed.
"I'm Amethyst, Amethyst Beat. Sorry that i couldn't say it earlier, but here it is. Heh.."
"Aw, it's no problem, Amethyst. My name's Sweetie Belle."
After a minute of talking, the two ponies exited the cell, ready to go thrue one of the endless tunnels.

"Are you ready, Sweetie Belle?" Amethyst asked the unicorn mare.
"Yes, i guess i'm ready."