Unwritten No. 3
Mobius, using the last ounce of strength he had, felled the wall with his pickaxe, and behold! The creature was there! It was vaguely humanoid in shape, and it had grotesque teeth. It proceeded to devour Langgud, and there, Mobius cackled like there was no tomorrow. To him, one of his adversaries was finally defeated, and he moved onto the next one. To his horror and dismay, he couldn't get out of the hidden cave room, even though it was wide open with no obstacles. It also never occured to him that there was no wall in front of the entrance, no guards chasing him, and the beast ignored him.
He was already apprehended by Loudwhisper herself, who knocked him out and searched the area for evidence, or more specifically, the sack with stolen tools, solid journal pages, blueprint scraps and misapproprated food and drink, which were now containers and flasks, specifically.
The irrefutable proof was shown to Sepsi herself, who in a fit of rage, sent Mobius down a specially created chute just for him. It had no way out, the walls were smoothed, removing any chance of escape, and the chute was covered by a trapdoor to prevent his fecal matter from defiling the atmosphere above. He was occasionally sent food and drink, and was forced to run a water pump down there, to actually serve the ponies instead of being a useless idiot bumbling around the fortress.
And he was none the wiser, for his life ended when he first woke up in a spacious pitch-black chamber of nothing, except sounds coming from above and the rushing water below the pump. He became utterly and irredeemably insane when he heard the words "Give up your plans, Mobius. Your days of terror have come to an end." from no one but Sepsi Crimsontail herself.
Since then, he's been stuck, babbling about his anger against everyone. Two months after his imprisonment, the inhabitant in the chute seemed to have kept silent, and as such, no food and drinks were sent down the chute anymore, assuming him to be dead.
But the people working near the chute reported back to Sepsi to have heard sad whimpering and crying, as well as painful groans deep down the dark chute.
((Why did I choose a Creepypasta ending?))
((To be more specific, Mobius was apprehended by Loudwhisper, and sent to a typical jail. There, someone (Langgud?) watched him bash his head over and over in an idiotic attempt to escape, but when Sepsi received the solid evidence that implicated Mobius in the crime, she sent him down the chute to keep him from terrorizing the ponies. He was knocked out in prison, sent down the chute, and when he woke up, Sepsi said something. The chute contains a water pump from a water source (cavern? aquifer?) that leads upwards into the main fortress.))
((Yes, this concludes Mobius' life story, but I could take over another character if anyone wishes.))