What if the fey were just fantasy cartoons? A dragon and an adventurer get turned into "fey" versions of themselves. Mature.
With each great footstep beat the heart of the mountain. With each fiery breath its treasures glimmered like stars. Scarce light filtered through the slits cut into the vaulted stone roof while the vast cavern turned every sound into an echoing chorus. Aluin huddled behind a gilded longship half-sunk beneath the dragon's hoard. One hand lay over her mouth and the other across her chest, as if to still her breath and stop her heart.
The dragon's voice cracked the dry air. "Trespasser! My flame has killed noble warriors—you should be honored to join their kind. Now show yourself, and I will be merciful."
The floor shuddered. The goblets and diadems beneath her began to slip away and rob Aluin of her footing. Clinging to the hull of the boat, she fought to stay above the tide of riches. The thundering footsteps were terribly close now. A gasp died in her throat as a claw as big as her head came to rest on the boat just above her. Silver and gold spilled across her shoulders like sand.
The shower of coins woke the elf-blade bound to her belt. It began to quiver and clatter, as if sensing danger and eager to be used. Scowling, she clutched it tightly by its hilt. She knew not what magic was worked into its blade; she had not yet needed to unsheathe it.
"My treasure is mine by right," the dragon said. He lifted his claw and beat his wings, rising into the air. "None can lay claim to a single coin of it. I am the King Beneath the Mountain. I am black smoke and the coming night. I am death and the ruin of cities." With a mighty crash, he landed in front of Aluin wings outstretched, fire brewing between his fangs. "I am Glaud!"
Gilt timbers groaned. The longboat listed to the side and spilled over. Aluin scrambled out from underneath it to keep from being drowned beneath a sea of silver. Now she stood face-to-face with the dragon. His scales were the color of porphyry, or dried blood, stretched taut across the sinewy frame of some great beast or tyger. Fangs filled his narrow snout and goat-like horns curled back from his head. His eyes gleamed yellow-green like tarnished gold.
She said, "I am Aluin." Where the courage to speak came from she could not guess. The elf-blade bucked and jostled at her side like an over-eager hound. "I come in search of a stone which belonged to my family generations ago, a sign—"
"You are a thief," Glaud snarled.
Aluin wrested the sword from its sheath. Its hilt was red and its blade blue, both blazing so bright it seemed as if they shone with their own light. From the hilt toward the tip, it thickened so much that she could not say how it had fit in its sheath. A shiver ran down her back and the sword wobbled along its length.
"I will not leave this mountain without that stone," she said.
Glaud's lips peeled in a beastly grin. "Then you will never leave."