If Leonardo had had hair on the back of his neck, he knew it would have been standing on end. The clicking sound was louder than ever — growing louder by the second, until it was all he could hear. He cast a desperate look at Don, who was standing wide-eyed on the other side of the door, his hands clenched in the air, looking for a bo that wasn't there. Leonardo knew how he felt — the absence of his katanas had never been so infuriating.
He could see the shape of 68-G now — long and sinuous like a Chinese dragon, but without any of that creature's implied grace. As it moved into the light, Leo saw that it was covered in thick gray skin like a shark's. Its long scuttling legs were almost bent double, its eyes were small and fast-moving, and its face was dominated by a small mouth with long, wicked, swordlike teeth — the source of the clicking noise.
"What the shell is that?" Leo said.
"Some kind of mutant," Don said unnecessarily. "A lab-made one, like the ones in the Underground."
"411-A is correct," the voice said pleasantly. "68-G is a failed specimen from the early days of the same project, but useful for determining the capabilities of other subjects."
68-G snarled at them, and clattered its teeth in a wordless warning. Its long tail lashed at the air as it looked between the two targets, seemingly weighing which one to go after first.
Leo had no idea how intelligent 68-G was. He just prayed it was dumb.
"Over here!" he bellowed, throwing his arms over his head. "You want someone to eat? Come this way and get me!"
"Leo—" Don called out, alarmed.
Leo let out an audible shout as he raced closer to the monster, then darted around to keep its gaze focused on him. "Come on, ugly!" he shouted again, retreating to a safer distance, feeling it watching him balefully. "Think you can take me on?"
"Leo, don't—" Don tried to say, but a sudden spasm caused him to double over.
Just then the creature snarled again, its teeth clicking, and surged towards Leonardo. He immediately regretted getting that close to it, as its spindly-looking limbs moved ridiculously fast — one of the clawed feet lashed out and left gouges on the walls of the area, which Leo barely ducked from.
Breathing hard, he backed away, and flipped high in the air above the monster's head, landing lightly on the wall of the arena before flinging himself off to the other end of the arena. He landed heavily, almost slipping on the sand under his feet, but managed to catch himself just in time to turn. 68-G was climbing up the arena walls like a caterpillar, sinuously slithering towards Leo with a fierce glint in its tiny eyes.
Suddenly the voice said, "Keep an eye on 410-B. His agility is quite astonishing, especially given his physical construction."
Leo gritted his teeth, and leaped aside from another swipe. He wasn't sure what the voice meant by "physical construction," but he suspected he wouldn't like it.
Then another man's voice spoke — a deeper, richer one. "Agreed, but what about 411-A? He doesn't seem to be participating in the fight at all."
And then a woman spoke up, sounding slightly irritable. "We can hardly expect approval based on only one specimen. The results must be near-uniform."
Who were these people? Leo's mind was spinning even as his body was, leaping aside from the creature and landing fierce kicks and punches on whatever parts of its body he could reach.
"Don't worry," the first voice said soothingly. "If necessary, 410-B will be removed from the fight altogether, and we will evaluate 411-A separately. This test is partially to determine group dynamics and how effectively 410-B can strategize."
Leo sprang off the wall, curving over the creature's writhing back, and brought his fist down in its leathery gray flesh. Then he felt something strike him in the shell, and suddenly he was flying through the air, shouting in alarm, before landing in a heap in the sand—
—"… observe his natural armor — a bony carapace that would preclude rear attacks from most conventional weapons, and a frontal torso design that would be resistant as well. Mother Nature's work, adapted for a more human frame."
"An interesting specimen," the woman's voice said. "But wouldn't those physical qualities also limit his fighting abilities?"
"Not at all. 68-G should effectively prove that…"—
Leo gasped, feeling something jar loose in his memory. Clutching the sides of his head, he stumbled to his feet just in time to see another claw swiping down toward him. White-hot pain flashed through his shoulder as it struck, and he was sent reeling across the sand, found himself gripping the wall with both hands as he struggled to regain his bearings…
"410-B doesn't seem to be doing as well this time around," the second man's voice said.
If Leo hadn't been so consumed with trying to survive, he might have told these unseen figures off for their callous observations of his fight. They were the ones who had meddled with his head, pumped him full of poison and pitted him against a monster. Then they had the nerve to complain that he wasn't fighting well enough?
He stood his ground, digging his feet into the sand and preparing to jump again — this time he would strike at its eyes, one of its few vulnerable spots he could see, even if it was alarmingly close to its very large, sharp teeth.
Suddenly a streak of green and purple soared over 68-G's head, and Leo barely had time to turn before he saw Donnie landing feet-first on the creature's serpentine neck. He was panting heavily and still looked ill, but he was still able to fight — or at least, more than Leo was at the moment. The creature uttered a deafening, whining noise that ended in a gurgle, and started twisting around, attempting to reach Don or buck him off.
"Don!" Leo shouted, launching himself into the air. He didn't have a lot of hope of actually landing in the right place — trying to estimate where a frantic beast with a snakelike body would be in a few seconds wasn't very easy — but he had to keep his brother safe from this thing.
He landed with a hard thump and what sounded like the crack of a fractured bone, at the shoulder junction between the creature's body and its spidery limbs. It let out a shriek of pain, and began twisting around in an attempt to get to him. Long glittering teeth clashed near Leonardo's face, and he felt hot breath that stank of blood and rotten flesh on his face.
He seized a handful of the creature's gray skin and vaulted himself up to where Don was crouching, his face blanched and one of his arms over his belly. "How are you doing, bro?" Leo whispered, putting an arm around him.
"I'll be fine, assuming this thing doesn't eat us," Don responded.
But then Leo heard something else — a hissing sound that seemed to come from everywhere and nowhere. With it came a sickly-sweet odor, as if someone had left candy out in the sunlight until it melted. Alarm bells began to ring in his head.
"Don, don't—" he began to say, only to feel a heavy weight crash into his shoulder as his brother's legs failed him. Leo wrapped his arms around the half-conscious Don and leaped away from the thrashing monster, landing heavily on the sand some distance away. But rather than the light, nimble landing he was used to, he landed like a lump of falling rock, his legs suddenly nerveless and weak.
"Leo—" Don croaked. "The monster—gotta get away—"
Leo wasn't sure if he meant that they both had to get away, or whether he was urging his brother to flee without him. Desperately, he wrapped his arms around Don and tried to heave him upright, but his arms refused to cooperate, muscles turning to jelly.
"Come on—Don—" he grunted.
But his brother's eyes were already closing, and his head slumped against Leo's chest. Leo crashed down to the sandy floor, his eyes blurring as he began to slip into unconsciousness. In the distance, he heard the creature roar once more, and then stop.
Dark figures scuttled through the arena, their voices oddly mechanical, some of them holding long objects that sparked. Leo struggled to keep his eyes open, and succeeded just long enough to see the alien visage of a gas mask looming over him.