There was something moving in the living room, hugging the skirting board. It moved out of sight behind a chair. Ellie froze and held her breath. Some of her brother's mechanical creations could only see you if you moved. He was going to be in trouble for this. It reappeared, strolling into the open, whiskers twitching, scaly tail dragging, matted fur revealing scabby skin. It was a rat.

“Jamie!” she screamed, and threw her coffee cup at the rodent. It jumped. The cup shattered where the creature had been.

“There's not much point in throwing things at them,” said Jamie as he swept up the pieces of her third-favourite cup.

It was bad enough losing the cup, but the fact that her brother was both innocent and now giving her condescending advice was almost unbearable.

Credit: JACEY

“They are so ugly. Can't you do something about them?”

“I could, but it means abrogating our treaty.”

In her view it was more a blackmail arrangement than a treaty. Under its terms Jamie agreed never to allow any of his creations out of his room and in return Ellie prepared a gourmet dessert or other treat every second day. She had to decide. Which was worse, Jamie's machines or the rats?

Jamie looked at her as if he could read her thoughts.

“I can give you a beacon that will inactivate any bot in a room you enter. I'll make it look like a pendant or something so you can wear it.”

“Oh that's nice. But perhaps you could make it something that I can wear under my clothes.”

Jamie was a genius with machinery but in Ellie's view his aesthetic sense left something to be desired. She couldn't be seen in public wearing some clunky piece of jewellery designed around a robot repeller.

“I'll have some prototypes out tomorrow,” he said.

****

“Jamie!”

He was in the kitchen a second later, much quicker than he had ever appeared before.

“Just got the signal from the bot. Good, eh?”

There was a rat on the floor emitting a high pitched squeal that sounded like a cat in agony, and dripping blood as it struggled to escape the bright needle-like jaws of a tiny machine that ran on tracks like a little tank.

“It's suffering. Make it stop.”

“You've immobilized the bot by coming into the room. Go back out.”

She took two steps backwards and the squeal went up in pitch and ended in an awful gurgle. She opened her eyes to see Jamie's machine drag the rodent corpse across the kitchen floor, leaving a trail of blood behind, and deposit it by the garbage container. She waited a few seconds to compose herself before going back in. It was important always to speak to Jamie in a calm and positive way if she was to get him to do what she wanted.

“Your machine worked very well but it did cause a lot of suffering to the rat.”

“There are plenty more rats.”

That was true. The warm, wet weather caused by the greenhouse effect favoured them, and ill-advised mass-poisoning programmes had produced pesticide-resistant animals — she had seen documentary footage of them seeking out poison bait and getting intoxicated on it, rolling around on their backs and then staggering off to recover.

“That's right. But we don't want them to suffer.”

“I'll increase the bite force ...”

“And we can't have blood on things. I know you can do this. Just find some way that we don't have to see these ugly things that does not involve killing them.”

****

A week went by. There were two more rats. Jamie spent every moment when he was not at school alone in his room, which was perfectly normal for him, coming out only to collect the packages he had ordered. Some were from biological suppliers instead of his usual electronics supplier. The weeks turned into a month. Ellie started keeping an old tennis ball to hand so that she had something to throw. She saw Jamie only at meal times.

He turned away questions about the de-ratting project with answers that were either too vague or too detailed to understand.

“And there are cockroaches too,” Ellie complained over a crème brulée she had made with fresh vanilla pods. She had served herself 50 calories' worth.

“I'll take care of them too. Sorry this is taking so long.”

Jamie had never said sorry to her in his whole life. She abandoned her plans to threaten him with a reduction in treats if he didn't produce. Jamie had never failed her yet. All he needed was encouragement.

In the second month, he stopped going to his Friday night fights; weird occasions where he fought his robots, like the one that had killed the rat, against machines built by other boys, and one or two girls, who were almost as strange as he was. She started cooking him an extra treat for Friday nights.

It was three months later when he called her to the living room. He turned out the lights as she entered and she saw fireflies in a bowl on the table.

“They're beautiful,” she said, wondering how they could be connected to the rat-elimination project.

Jamie switched on the lights and they weren't fireflies at all. They were the most beautiful insects she had ever set eyes on, with shells of bright metallic green, silver and red. They were like nothing she had ever seen but somehow familiar too.

“Glad you like them. Now check this out.”

He whipped the cover off a cage revealing an adorable little animal with a long, sleek golden coat and a fluffy tail.

“Good, eh? And they are great breeders. I have a bunch out now, hybridizing with the local population. Soon your problem will be over.”

“What? Do these eat the rats or something? Do they bite?”

She withdrew the hand she had put out to stroke the lovely little thing. It looked up at her with beady eyes, whiskers twitching.

“Jamie. This is a rat!”

“Of course. But it's cute, like the cockroaches.” He gestured at the bowl of insects. “Soon they all will be. No more ugly pests. Isn't that what you wanted?”