Typically for prompts I set my story in realistic modern times, but I just couldn't make it work for this one. Introducing magic was the only way I could keep the story from going dark (not that that's necessarily a bad thing, it just wasn't what I was in the mood to write).
So here you go:
“You shouldn’t be using your magic to kill birds,” Ammie declared firmly.
Kiv jumped, having assumed he was alone. “It’s none of your business,” he snapped at the wiry ten year old; though he felt an immediate pang of guilt that he’d been caught.
“You killed the chickens last week didn’t you,” she pressed. “Daddy had to buy more you know. He wouldn’t have needed to if you hadn’t killed them all.”
Kiv grumbled angrily and turned away. It had been easy for their father to assume some animal had snuck into the coop and slaughtered the chickens – there’d been enough of a mess for sure. To avoid suspicion though, Kiv had shifted his focus away from domestic fowl and instead continued to refine his technique by sniping birds off tree limbs. He could finally do it now without making them explode. It was wholly satisfying and he hadn’t felt the least bit bad about it until now.
“I’m eighteen,” he declared haughtily. “I can do what I want!”
“Why are you killing them?” she countered.
“For what? For killing us?”
Kiv stopped and looked at his little sister, surprised. He saw in her innocent eyes that she was only being abstractly philosophical, that she didn’t truly believe her brother would murder his family. Still, he imagined the direction his little games could easily go if he continued and the wind instantly wafted from his sails.
“No,” he replied humbly. “It was just something fun to do…” and he realized how empty his words sounded.
“You have all that magic and the only ‘fun’ you can think of to do with it is killing birds?” her hands were on her hips now; so like their mother.
The young man smirked and caused a puff of air to kick up a moat of dust in front of his sister. She sneezed, as he knew she would, and they laughed.
“Well,” he replied. “What fun do you think I should have with my magic?”
Ammie thought for a moment, giving the matter serious consideration. Finally she suggested, “Daddy was thinking about felling some trees at the north end of the wheat field. I bet you could blow them up right at the base and make them fall down easily.”
Honestly he’d never tried using his powers that way but it was in line with how they worked. “Alright then,” he replied with a chuckle, taking the hand of his ingenious sister. “Let’s give it a try!”