Disclaimer: I don't own Adventure Time.
"Are you okay, bro?"
That was the first thing Finn heard as he stirred awake. He looked about half-asleep, and jerked awake as he saw the smoke and steam emanating from the pile of rocks that was once the Fire Kingdom.
"Darn it!" he yelled. "The Fire Kingdom, it's destroyed! I'll kill that monster!" Finn looked back at Jake and his friends. There stood the Ice King, Marceline, Water Princess and Flame Princess. Everyone of them looked upset (save for Marceline, who only looked angry). He took a closer look at Flame Princess. He expected her to be angry or sad, but her only emotion, it seemed was defeat. he had had enough. He dragged himself up.
"C'mon," he said. He picked up his sword and backpack off the ground. His white hat and clothes had torn slightly. He gripped his sword tightly, ready for his revenge. What had just transpired was unforgivable. Not one, but two kingdoms had just been destroyed, and there were many more in danger. They noted that the Slime Kingdom was next (as the monster was headed n that direction), and they turned back to the half-melted Candy Kingdom, where the princesses were standing.
Princess Bubblegum was in front of everyone, staring at her once giant tower. All the citizens had evacuated, and only Stormo and Goliath remained. "What was that thing?" asked one of the princesses.
"Whatever it is, I'll make sure it's defeated. Hero's honor." replied Finn. He began to chase after it. Jake, Marceline, and Ice King went with him. They arrived at the Slime Kingdom, now being hardened by air that the monster was spitting out, now with slightly white crystals. Finn ran up to the monster and jabbed his sword at it's back. The sword barely pierced it's rock-like body.
Then, Finn found himself being thrown back, and out of the shadows appeared the Keeper. "Well now, what do we have here.?" The Keeper pulled out a sword. He struck at Finn, but Finn parried it. Finn tried swinging his sword at the Keeper, knowing full well he was behind everything. He missed and ended up getting sliced on the cheek. So the sword fight began. For a long time, they did not damage each other, until finally the Keeper cut Finn's eye. Now half-blind and lacking some depth perception, Finn missed swing after swing.
Finn kept on trying to hit the Keeper, while the latter simply dodged. "Fool," the Keeper said. "Do you want to die?" With that, he struck Finn, who was barely able to block it with his own sword. It was then Finn really took a look the Keeper's sword. It was dark grey, almost black, and it had what appeared to be some sort of early human skull attached to the bottom. The skull had red jewel eyes, and the hilt was silver. As they struggled with the clash, Finn's sword, one of his most precious, treasured objects, had cracked and shattered.
Finn was paralyzed. He had not time for anger though, as he felt a very sharp pain in his arm, and looked down to find that it was cut off. As the Keeper fled, Finn fainted from exhaustion and blood loss. As his friends were busy fighting off the monster, a small ship came by and abducted Finn.
Finn woke up in a white room, a shadowy figure looming in front of him.
"Hello there, Finn the Human."