Vailed In Shadows || 2012! Leonardo x Kunoichi Reader || COMPLETED ||

Note: This chapter is long—
with a total of 2890 words

The large, curious eyes of the turtle in the purple mask stayed fixed on the glass test tubes in front of him. Droplets of glowing green liquid trickled from one tube to the next, blending with the artificial blue mixture he’d carefully concocted. The liquids merged, swirling and shifting in color, until they settled into a pale yellow hue. 

“Fascinating,” Donatello muttered under his breath, leaning closer for a better view. 

From behind him came a loud, exaggerated groan. “Ugh, booooriiiiiing!” 

Donnie sighed, already knowing the source of the complaint. He glanced over his shoulder to see Raphael slouched against the desk, wearing his usual look of disdain. 

“What would you know about it, Raph?” Donnie shot back, arching an eyebrow. 

“I know that you’re a complete nerd,” Raph replied flatly, a smirk tugging at his lips. 

Donnie rolled his eyes, turning back to his experiment. “I’m studying the mutagen, trying to understand its properties—what it’s capable of beyond just causing mutations.” 

Raph snorted in response, clearly unimpressed. 

Before Donnie could fire off a retort, his attention was drawn back to the tube in his hand. A strange smell had begun to waft through the room, sharp and acrid. He looked down just in time to see the yellow liquid darken to a vibrant orange. It bubbled furiously, turning a deep red before— 

“Ah!” Donnie yelped, instinctively flinging the tube across the room. It clattered into a trash can and exploded with a small *pop*, sending a puff of smoke into the air. 

“Well, now that was actually cool,” Raph said with a chuckle, clearly amused. 

Donnie ignored him, muttering under his breath as he stared at the now-empty trash can. “At this rate, I’m going to run out of mutagen to test...” 

“Leo’s out scavenging for more, isn’t he?” Raph asked, pushing off the desk. 

“I told him not to go—it’s the middle of the day! But of course, he insisted.” 

Almost as if summoned by their conversation, the lab door swung open. Leonardo staggered in, looking far worse for wear. He carried a canister of mutagen in one hand and a grappling hook in the other, the latter dragging limply behind him. His mask was askew, dirt smudged his green skin, and his ankles bore fresh rope burns. 

“This thing,” Leo grumbled, waving the grappling hook in frustration, “is broken.” 

Neither Raph nor Donnie paid much attention to the device. They were too focused on Leo himself. 

“What the shell happened to you?” they asked in unison, sharing a glance of disbelief. 

“Where do I even start?” Leo groaned, hopping onto the counter to sit. “Let’s see—fought some Foot soldiers to get this mutagen, embarrassed myself in front of (Y/N)... oh, and then a group of kids chased me down an alley and pelted me with rocks.” 

Raph burst into laughter, nearly doubling over as Donnie tried—and failed—to suppress a grin. 

Leo’s eye twitched as he watched his brothers revel in his misery. 

Finally catching his breath, Raph managed to say, “I don’t know what’s worse—the rock attack or you making a fool of yourself in front of (Y/N). Again.”