They put down plastic first. It's a little uncomfortable, but it's a necessity at this point, and to be honest Karai finds something kind of soothing about the soft crinkle as she settles down onto the mattress. It feels like it's part of the ritual.
She shrugs out of her clothes, skin already turning to scale. By now, the transformation is as natural as using her sword, the snake-body settling in around her like a warm blanket. Karai leans back with a sigh, muscles stretching and folding into new shapes.
A lot of the time it's easier to be intimate when she's clothed in a reptilian skin, easier to touch and be touched without remembering everything that's been inflicted on her fragile, human body. The scales are a wall keeping out memories of bruising hands and Shredder's voice growling in her ear, leaving her alone with her own body and her own heart beating steady. 
A forked tongue flips out of her jaws to taste the air. She already knows who's with her, of course, but she could have been dropped in this room deaf and blind and she'd still know those scents as well as her own. Leo on her right side, Shini on her left.
They kneel down beside her quietly, almost solemn. They're both naked as she is, dim light flowing over their muscled bodies. Leo's callused finger traces her shoulder, while Shini's hair, still rich with the scent of herbs, brushes across Karai's face as she kisses her on the neck.
After a lot of exploration and way too many hours on herpetology sites, they've got a decent idea of her erogenous zones. She watches them kiss up and down her body, managing to remain relatively quiet despite the crinkling plastic as they shift from place to place. Their mouths brush against sensitives, stirring up warm little flickers of pleasure.
It's good, safe, but it's also too soft, and she starts to squirm. Shini chuckles as she moves farther up Karai's face, planting kisses over her cheeks and eyes. "Impatient already, senpai?"
"You two are sssssslowpokessss," she mumbles, rolling acid-green eyes. Leo hmms and sinks his teeth into her arm.
"Nnh!" Karai's coils ripple, caught off she always is by this first sharp burst of feeling, the flickers of pleasure turning into something sharp and bright. Leo lifts his head and grins wickedly at her, the first few flecks of tonight's blood already glistening on his lips.
She throws her head back, giving him permission to bite again, and he does. Karai groans at the burrowing of teeth burrowing through her scales, cutting through her barriers, leaving her raw and bloody and real.
Shini settles back on her knees, observing Karai thoughtfully. "How's it taste, Kappa?"
"Okay." He smacks his lips, blinking down at Karai "Are you using a new soap?"
Before Karai can answer, Shini's eyes flash gold, and when she opens her mouth again her teeth are gleaming points. Then she's hunching over Karai's side, biting deep with a soft moan of satisfaction, raising her head to reveal a scale glinting in her teeth like a prize.
And they're both devouring her at once, tearing at the most sensitive parts of her body until Karai can barely breathe. It hurts so bad, but fucking hell, she loves it. This is pain she's chosen, been given as a gift, and it's intoxicating.
She writhes at the scrape of teeth against her skin, breath hitching as they bite over each other's marks or lean over body to kiss, letting her see the blood dripping from their lips. They swallow her bit by bit, consuming flesh that mutant healing will replace in the morning, until Karai's flesh is made entirely anew.
Tonight, she is goddess and sacrifice both, and they are the ones kneeling at her altar. Leo and Shini feed off of Karai, blessing her with their hunger, their need, their painful perfect love. She could lose her mind like this, beg them to eat her whole as she lets herself be reduced to pure flesh.
But she can't, at least not entirely. She has obligations, after all. Gathering her few scraps of self-control together, Karai lets a snake-arm gently wind its way up between Shini's bare legs. She yelps, sinking her teeth even deeper into Karai's tail a finger-tongue savors the taste of her already damp sex. Shini whimpers, grinding down on her.
"N-now who's impatient?" Karai grits out. Shini rolls her eyes, although Karai can hear her breath picking up.
Her gaze flicks to Leo, currently nibbling at her tits. His eyes are sharp and wild as cracked glass, crazy in a way he almost never lets himself be, and it's so beautiful it hurts. She nudges up against his slit and he churrs softly as his cock spills. The vibrations pulse through her torn flesh, sending her head spinning.
"So beautiful," Leo rasps. "You're perfect, Karai."
"Ob-obviously," she huffs.
"We'd--we'd settle for nothing less," Shini chimes in, before dragging her teeth across Karai's stomach. Leo, who was leaning towards the same spot, huffs and settles for Karai's neck instead, nibbling past her jawline to bite at her cheek. She squeezes his cock and he whines, the sound echoing in her ears.
Karai can't really only do so much for them in the state she's in, but luckily Leo and Shini do a very good job of grinding down on her snake-hands, until their mouths are trembling as they press them to her skin. The crackling is louder than ever, drops of red splashing the plastic, but for some reason Karai likes the background symphony.
She starts to hear herself letting out frantic little hisses, tail slapping wildly against the mattress. By now, Leo and Shini can tell what she needs without her having to say, finally using their hands to caress the most sensitive areas of her body, dragging her fingers over her now-glistening scales as if she wasn't already close enough to losing it.
And just like that, she does, head slapping against the mattress as her tongue flops out like a goddamn dog.
They make her shudder again. And again. And again, because they say like the way her pleasure tastes, that it "spices the meat" or some shit like that. Karai doesn't know, and really doesn't give a shit. What matters is how incredibly, impossibly loved she feels, loved to the point of going crazy with it.
Shini comes at some point, her high-pitched crying ringing through Karai's own haze as she tightens around Karai's snake. But she keeps grinding down relentlessly, managing to come one last time before they finally let Karai collapse in a heap.
Leo's a master of control, of course (the only way he can keep up with them) and he's the one who comes last, squirting down her snake-throat at the sight of Karai slumping onto the mattress, sweaty and bloody and trembling.
The taste of semen on her snake-tongue wakes her up, at least a little, and the snake eagerly drinks Leo down as he comes and comes, because turtles can come a lot. (One of the few functioning bits of Karai's brain reminds her to try and talk him into letting her time it at some point.)
For a while they all just huddle there, slick with each other's bodily fluids, saturated with the scent of each other’s pleasure. Karai gazes up at Leo and Shini, feeling the same blank adoration she can see in their eyes.
Shini collects herself first, rolling off the mattress with a grunt to grab her bag of herbs and bandages. The sound triggers Leo into motion and then he's moving to put himself away and help Karai up.
She lets herself shift back to human, because she doesn't feel so exposed with blood crusting over her skin. Leo carries her to the bathroom while Shini puts the plastic away to be washed later.
The three of them share tired, happy kisses as they clean off. Shini tends to Karai's wounds, with Leo occasionally stepping in to soothe the bigger bites with his mantra--she'll heal quickly either way, but it feels nice to be cared for.
Karai pushes her limbs into motion, running a comb through Shini's long hair and scrubbing at the blood collected between Leo's scales. Shini dons a foam mustache and they all laugh as pink swirls around the drain.
Afterwards, they gather on the (plastic-free couch), talking quietly about ordinary things. Karai lets herself snuggle up between Leo and Shini, feeling their strength in their bodies and the steady beating of their hearts.
She may have been devoured tonight, but she's never been happier to be alive. "I love you guys," she whispers.
"I love you, Senpai, in all your tasty goodness," Shini says. "And I love you, Kappa, even if you chew up the good shoulder before I can."
Leo rolls his eyes. "I love you both, too," he murmurs, planting a kiss on Karai's head before picking up Shini's hand to kiss her knuckles.
Karai reaches out to squeeze their hands and they squeeze back, relishing each other's touch like a fine meal.