Thunder Bumper

An electric crackle echoed through the lab and Cassandra paused to glare at the gold-rimmed bell jar on the shelf. “No,” she said flatly, “I’m not letting you out.” The jar boomed and shook with thunder. “The last time I let you out, you destroyed three experiments and made Davis’s hair stand on end for a week.” Lightning sparked off the gold bands surrounding the crystal cage, then a distinct, whining sound made the shelf vibrate and rain began to fall inside. “Crying about it won’t help you.” Cassandra turned her back on the sulking elemental. She could hear the lightning running and sizzling around the bands, singing in its frustration while the miniature storm raged inside.
“Why is the jar crying?”
Cassandra smiled as Davis sat on the stool next to her, his black eyes glittering. “He wants to come out,” she told him and reached to rub her thumb against the blunt end of his horn. “I told him no.”
“He’d be good this time, though, wouldn’t he?”
The jar rang with a clear, vibrant note and they both looked to see the elemental, condensed down into a humanoid form, pixie-ish with a shock of violently yellow hair and fingers that sparked. He pressed against the glass and pushed his nose just below one of the bands, eyes pleading. Cassandra glanced at Davis, who watched with the empathy of his race shimmering in his face. “I’ll put you on a god-damned leash,” she snapped at the elemental, who cartwheeled and thundered in delight as she reached up to remove the bell jar. “Only because Davis forgives you,” she hissed and he nodded solemnly before bounding down to buzz and crackle around the unicorn’s head, charging his hair with static and tickling a wild giggle out of him.