It's funny how even the softest materials can feel uncomfortable if you pull them tight enough. Shini wriggles, almost on instinct, in her restraints, feeling the silk tug gently over her flesh. Even the blindfold seems to dig in, wrapped nice and tight around Shini's head so that not so much as a sliver of light can get in. 
A hand comes down from, seemingly, nowhere, smacking her across one nipple. "Stop that." 
Shini's taken punches to the gut from metal fists without crying out, but she lets out a little whine now, pouting. Karai lets out a low huff, hand reaching out to grab Shini's chin in an iron grip. "Do I need to gag you?" 
For a second Shini considers playing petulant, but no, that would be too predictable. Instead, she gives Karai's hand a humble, kittenish lick, bowing her head in apology. 
Karai lets out a low chuckle. "Giving in that fast, huh?" The bed creaks as she climbs on, scales and flesh flowing over Shini's thighs. "Get a little damp and you crumble like a house of fucking cards." 
Her hand slips between Shini's legs--or, rather, slithers. Shini lets out a soft gasp before she can stop herself, trembling all over at the flick of a warm, damp tongue poking gently at her clit. Then it's gone, and she lets out a groan. 
"Needy slut." Karai reaches out to feel Shini's breasts, paying special attention to her aching nipple. She gives it a vicious twist and Shini whimpers, not even bothering to hide the way pain makes her writhe in the sweat-damp sheets. 
"I could rip you apart and you wouldn't even care, would you?" Karai purrs. "Feed on you for days, bit," she pays a sharp-toothed kiss on Shini's neck, "by bit," another kiss, on her collarbone, "by bit," a third kiss pulled across her tender aching breast, "by bit," Karai's mouth pulls down her chest, nuzzling the hair there, "by--" 
Karai's mouth presses to her cunt and Shini sobs, throwing her head back. Karai's always had a mouth like something holy and it's only gotten better now that she has a long, flexible tongue to bend to her wicked wills. 
Then are her other hands, still pressed against Shini's breath, but now sprouting significant teeth that scrape oh-so-delicately against Shini's breasts, a heartbeat away from spilling blood. Twin tongues lap at her nipples hungrily, forcefully, like they could rip her apart in a heartbeat if their mistress so pleased. 
Shini's senses are turned up to eleven in the darkness like this, the feeling of utter helplessness zinging across her skin. She can feel Karai's eyes dragging over her, Karai's want stripping her to the bone, and she can barely breathe with it. She almost wants to suffocate in it. 
Karai jabs her tongue in a pitch-perfect way and Shini lets out a hiss, trembling in her restraints. Silk it may be, but she swears it's going to leave bruises tomorrow, and she'll love it. She'll get Karai to kiss each other better, just to feel those beautiful mouths undoing her all over again. 
But then Karai yanks her hand away again and Shini sobs this time, jerking her hips in frustration. Or at least she does until she feels a fang brush through the hair over her cunt, freezing her still. 
"You want me to rip you open?" Karai whispers. "Cut all the need out of you. I can, you know. It'd be easy." Another moan spills out of Shini at that, loud and shameless. 
"Oh, stop it." Karai barks. Her voice is shaking ever so slightly, but Shini can still hear her rolling her eyes. "You need to learn that not everything is about you." 
Shini gathers herself enough for a taunting giggle. "Not about me? Why, what a silly idea--" 
Karai's hands shift back to human in a blink, a vicious slap coming down on her pussy. Shini shrieks, her cry splinters off into a gasp for air as Karai climbs on top of her. 
She's on her back in such a way that it's easy for Karai to straddle her face, muscular thighs, cool and smooth against her cheeks. Her nostrils flare at the sweet, sweet scent of Karai's want, deep and rich and more glorious than words can say. 
"Be a good girl," Karai growls, and before Shini can pull her brain together enough to quip, Karai is sinking down on her face. She only has a heartbeat to draw breath before she goes under completely, the last of her senses drowned out by her Sensei's sound, pressure, heat, taste.  
Shini has lived a long time, experienced all sorts of wonders and horror, had her fill of fine foods and finer genitals aplenty. But she's never tasted anything that could make her tongue feel like it could bleed light before, at least not until Karai. 
Her mouth moves frantically, hungrily, like she's in cat form and desperately tearing into a juicy mouse. Karai rocks back in kind, riding Shini's face with abandon, unrestrained and free to her wants in a way that Shini wishes her senpai could be more often. 
Scales buzz and hum in and out of existence against Shini's mouth, the pussy she's devouring seeming to almost blur at the edges. That just makes her work harder, of course, determined not to let a touch of shapeshifting stop her. From a distance she can hear Karai's snakes hiss with triumph, and the sound is enough to send her whimpering happily into Karai's cunt. 
Her own cunt is desperate, aching, her hips trembling as she tries to grind down on the mattress. For a distance she thinks Karai laughs at that, but it's hard to tell with the sounds of Karai's flesh squelching and shifting, drowning everything else out. 
Shini wants to touch Karai, touch herself, touch everything, but the silk won't let her go. Not that she really wants to break free of Karai's beautiful display, but it's the principle of the thing that drives her insane. 
All she can do is devour and let herself be devoured, lie there like a meal and be overtaken. All she can do is everything she wants to do, right now, and she lets burn with the glory of that. 
Karai isn't exactly concerned with preserving Shini's air supply, and that's okay, but neither is Shini. When her head starts going light, she barely notices, distracted by the way Karai's pace is picking up and the way her thighs have started to clench and flex. 
Beings like Shini don't need air quite the way other creatures do, and she can handle being a little light-headed for a while. She can feel herself slipping towards an edge, though, her world sinking down to the single, endless movement of Karai humping her face. Shini could pass out like this and be perfectly happy with the outcome. 
Karai, of course, knows her body too well for that. She knows how to time it when they're both splintering out at the edge, the perfect moment to shake and shudder and fall apart on Shini's tongue, blessing her with a mouthful of sunfire. 
Shini has never heard a sound like the one Karai makes when she comes, either. She just knows that she wants to hear it every day for the rest of her life. 
There's slick dripping down her chin as Karai finally slides off, warm and thick on her lips. Shini could go out on the town painted up like this--except she can't, because her cunt is still a tight, desperate little knot of heat, the cruel restraints still holding her fast. 
Karai slumps over her, panting, not moving back between Shini's legs, even though her nostrils are flaring and she has to smell it. No, she just looks down at Shini with that smirk of hers, and Shini can't hold back anymore. 
"Please," she whimpers, with a voice like shattered glass. "Please please please--"  
Fast as...well, a striking snake, Karai's hand blurs into its scaly form and plunges between her Shini's legs. It only takes one vicious suck, one final push, and then she's coming with a yowl, loud and jarring and without a single fuck left to give. 
"That's it," Karai whispers in her ear as she pants and shudders, choking on the aftershocks. "That's it." Her hand runs through Shini's hair, soft and gentle, and if anything was going to make her weep tonight it'd be that. 
Her restraints feel more like they're holding her together, now, and Shini sags into them gratefully. Karai seems to see this, because instead of trying to pull away she just snuggles a little bit closer to Shini, fresh scales rustling to life as coils slither over Shini's prone form. 
"You did so good for me, love," Karai whispers, pulling her tail tight. "So good." The blindfold is tugged away, and Shini blinks at the carefully dimmed light, trying to reorient herself and Karai in the damp, hot, lovely mess of things. 
The coils shift slightly, lifting Shini up enough for Karai to tip a few mouthfuls of water in her mouth. Shini lets out a soft sigh between each swallow, the tension slowly draining out of her as reality asserts itself. 
"Thank you," Karai whispers, and Shini doesn't have to ask for what, because she knows Karai means more than words can say. Her hands shift to work, slowly and carefully tugging each strand away; she bends her head to the important task of rubbing life back into Shini's body. 
In moments like these, they're so close together it's impossible to tell where the heartbeat pumping gently, steadily, safely, through Shini's bones is really coming from her. in moments like these, Shini thinks, little distinctions like that don't really matter.