AN: I came across this piece in my files while searching for something completely different; I think I posted it on Tumblr a couple years ago? Anyway, it's probably about time it made its way here!

Just crack the spine, Tian told himself desperately as he watched half a dozen white-furred, red-eyed rats exploring their opaque plastic tub. It's easy; just one pop. They won't feel it if you do it right; that's what Mr. Weilan said.

He released his white-knuckled grip on the edge of the metal table and reached over the shoebox-sized tub. One of the rats saw him; instead of running to the other side, it walked towards him and stood on its hind legs to sniff his finger.

Tian jerked his hand back; the six rats startled as one and sprang into the far corner to freeze stock still, all except for their twitching whiskers. Then slowly, seeing no danger, they began to creep forward and explore once again.

"What are you waiting for, Brother?" Xing asked. She stood beside him, watching the rats without the least bit of interest.

"Maybe you should show him how it's done, Bai."

Tian tried not to flinch at the sound of Mr. Weilan's voice coming over the audio system. Their trainer was on the other side of a two-way mirror, in a separate room; none of their trainers liked to get too close to Xing whether she was using her powers or not. It made him feel like he was a rat himself, caged and watched.

Xing didn't seem to mind it; she darted her hand into the tub and pulled out a squealing rat by its tail. Tian wanted to look away, but he was too frozen in horror. The rat looked huge in Xing's small hand, bigger than any of the fish that they'd ever caught from the lake. His sister eyed the rat coldly as it flopped back and forth, trying to free itself from her grasp. Then a red spark glowed from the depths of her pupils; her thin form outlined in an eerie blue light and with a pop and an acrid scent of ozone, a bolt of electricity flowed from her fingers, down the rat's tail and into its spine. The animal jerked once, then was still.

"See, Brother?" she said passively. "It's easy."

The rat fell with a heavy flop onto the table; Tian couldn't take his eyes off of it, despite the bile rising in his throat.

"We're practicing cervical dislocation, Bai," Mr. Weilan's voice said. "You'll have plenty of time to play with your power later. Do it the hard way now. Crack the spine."

The corner of Xing's mouth turned down slightly at the order, but she reached into the tub again while Tian watched, sweat beading on his brow. Mr. Weilan was going to make him try next, he knew it.

He also knew that he wouldn't be able to do it.

The remaining five rats were still blissfully exploring their cage; a couple were standing up and sniffing the air, no doubt trying to figure out what that whiff of ozone meant but apparently unaware that their cagemate was lying dead a foot away. Or maybe they did know, and just didn't care. They were rats, after all. Like the rat that Tian's class had kept as a pet last year.

He forcibly pushed that memory from his mind. That world didn't exist any longer. He wasn't Tian anymore; he was Hei, and his sister was Bai.

She had pulled out another rat. Instead of holding it up by the tail, she dropped it onto the wooden tabletop and pinned its shoulders between the thumb and index finger of her other hand before it could scrabble away. Her hand barely fit around the thick neck.

Immobilize the head, Tian remembered Mr. Weilan saying, and pull the tail and shoulders back to separate the cervical vertebrae. Hard. Rats' spines are tough.

Xing did exactly as Mr. Weilan had shown them; but instead of a quiet pop and instant death, the rat screamed and began to flail wildly beneath her hand. She frowned and pressed down, trying to keep it still, but the added pressure just made it panic more. The rats in the bin were screaming now too, scrabbling desperately at the plastic sides in an attempt to escape whatever was torturing their friend just out of their sight.

"Xing, just kill it!" Tian shouted, his teeth on edge from the painful cries of the animal.

"Mr. Weilan said not to use my power," Xing said. Gripping the rat's tail, she pulled again; the rat screamed again, and this time it managed to twist in her grip. She gasped and pulled her hand back, a trail of red droplets falling from her finger to the table.

The rat tried to drag itself away, but she had injured it enough that all it could do was stagger a step or two at a time. Xing watched it, and the horrible cold light ignited in her eyes again.

Tian couldn't take it. He couldn't take the squeals and screams of the rats, and he couldn't take seeing his sister lash out with her inhuman ability on a defenseless animal. As she reached for the injured rat, he pushed her hand aside and pinned the rat's head, just above the shoulders.

Just crack the spine, he told himself. It's painless if you do it right. It can't - it can't stay like this.

He pulled hard on the rat's lower body as he pushed its head in the opposite direction. There was the faintest of pops, and he felt something tear. The rat went limp in his hand, and he dropped it as if it had bit him. He stared, his heart pounding in his chest; its body was still.

The other rats were silent now. Tian wanted to throw up; but at least they were quiet.

In his peripheral vision, he saw his sister start to sway on her feet.

"Xing!" He caught her shoulders and helped guide her down to the concrete floor, her eyes fluttering shut. She'd only used a tiny bit of power; she'd wake up again soon.

He crouched there, holding her in his arms, until Mr. Weilan's voice crackled overhead. "There are four rats left, Hei. Continue the exercise. And remember, your sister's name is Bai now."

"But," Tian stammered, "I already…"

"Yes. And a sloppy, disgusting job you made of it. We're only interested in professionals here. Your sister has already proven her devotion to her training."

"I know, but I'm going to be her bodyguard, right? Just protect her. She can - she can take care of the rats on her own, with her power."

He didn't want her to. He didn't want her to be anywhere near this place, learning these horrible things. But they couldn't go home; there wasn't anywhere else for them.

"And if it isn't a rat?" Mr. Weilan asked. "If it's an assassin coming to kill her, and she's paying her price? What will you do then?"

Tian looked down at his sister, curled in his arms. The tip of her thumb was just brushing her lower lip; he watched as a drop of crimson blood fell from her finger to bead in the corner of her mouth.

He closed his eyes and swallowed hard. "Crack the spine," he whispered. Lowering her carefully to the cold floor, he stood and took a deep breath.

Then he reached into the tub.

It's painless if you do it right.