It doesn't happen on purpose. Great things never do, Blaine thinks, and this is definitely a great thing.

Kurt's house is empty and they're making out, quite heavily, like they tend to nowadays when the worst (or best, Blaine thinks, because there was nothing wrong in their first time) is behind and they don't have to feel too shy around each other. Kurt's hands are on Blaine's lower back and he's making those little whimpering sounds into his mouth, and Blaine would think that he's in heaven if he believed in things like heaven. Kurt's mouth is warm and tastes like apple bubble gum and something that must be Kurt, and every time he does that thing with his tongue Blaine feels like flying. He's purring, too, quietly and subtly deep in his chest, his nails clawing the skin of Blaine's neck as gently as he possibly can.

When Kurt starts to squirm under him, his tail fluttering restlessly and his ears twitching, Blaine decides that it's enough, struggles to get his lips off of Kurt's, trails them down his neck instead, and Jesus Christ the noise Kurt makes. He's not quite over the fact how vocal he can be, and Blaine buries his face on the small space on the mattress between Kurt's neck and his own arm, trying not to moan aloud.

"Jesus, Kurt", he says when he's positive that his voice works again. "Jesus".

Kurt giggles breathlessly, his eyes dark and tail still swaying from one side to another and Blaine finds himself following the motion of it before attacking his lips to the nape of Kurt's neck and biting.

The effect isn't what he expected. Sure, he's kissed and sucked and licked and bit his neck countless times before, but somehow never the back of his neck, and wow, okay, fuck it, this is so hot Blaine thinks he's going to explode.

Because suddenly he has Kurt fully underneath him, whimpering and his legs falling open, and fuck, if that isn't hot. His eyes are closed and his tail has stopped moving, his whole body boneless and submissive, and Blaine has to struggle hard to not moan against the skin of Kurt's neck.

This shouldn't have been as much a surprise as it was, because well, okay, Blaine knew that Kurt had some… cat things he couldn't control, but he always thought they were mainly the purring and the tail movements (and the hissing, when he was too angry for words). If he had known about this… God, the things he would have done to him earlier, he thinks and shudders at the thought. But he hadn't, so instead of stopping he bites in deeper, harder, but not even nearly enough to draw blood, and Kurt mewls and spreads his legs even further apart, and Blaine thinks that he could come from the sight alone. Kurt is usually so controlled and shy and the way he's spread on the bed like this, his chest heaving as small purrs and mewls make their way through his throat make Blaine positively ache. In more places than just one.

Blaine is nothing but a gentleman, though, so as he finally focuses on breathing instead of the feeling of Kurt's erection against his hipbone and the way he's still whimpering, he closes his eyes and lets go of the skin he still has between his teeth. When he finally manages to collect enough of a mind to remember that he never asked Kurt if it was okay, he panics slightly (because he's not the type of a person who just takes advantage of his blissed out and a bit out of it all in general boyfriend, no) and backs off slightly. Kurt's eyes are heavily lidded, the blue behind the eyelids is clouded by something dark, and he whines gently when Blaine removes his body reluctantly from Kurt's, moving next to him on the bed instead.
"Are you okay?", he asks, hoping that he sounds as concerned as he feels, but as he hears his own voice, husky and raspy, he internally winces. Okay, no. That didn't go well at all. But Kurt only whines, sounding a bit more needy this time, and tries to pull Blaine back on top of him. Blaine chuckles lightly.
"I take that as a yes, then?" and grins widely at the incoherent sounds Kurt makes in reply alongside with the nodding.

So Blaine attacks Kurt's lips once again, and okay, he's still quite a lot of soft and submissive, Blaine finds out as Kurt lets him gladly do anything he wants, whimpering gently into his mouth every now and then. It makes him feel weirdly powerful and trusted, but vulnerable and scared, too – they both know how much it takes from Kurt to trust someone enough to let them take control and take care of him even if it's only kissing. (At least Blaine hopes it's because of him, even if only a little bit, and not entirely because of how the neck-biting effects him. Then again, Kurt probably wouldn't let just anyone bite the back of his neck if that's what it does to him.)

Blaine takes his time kissing him, just enjoying the feeling of Kurt's mouth on his and his body against him, taking in the smell and taste of him while his eyelashes flutter against his cheeks. Kurt, however, is getting more and more impatient second by second, and Blaine has to whimper a bit as he remembers how tight the jeans Kurt is wearing really are, because shit, that must hurt. So, involuntarily he removes his mouth from Kurt's long enough to kiss his cheek quickly and start unbuttoning Kurt's navy shirt while looking in his eyes, reassuring and asking "is this okay?" and "are you sure?", and Kurt smiles in reply, lifts his left hand to lazily unbutton Blaine's shirt. Once they're out of their shirts (and after Blaine half-casually reached his hand to stroke at Kurt's ear and watched with a half-amused expression as he leaned against the touch, melting into a puddle in his arms) Blaine honestly can't wait any longer, and his lips find Kurt's once again in a almost rough kiss as he moves to unbutton and unzip his jeans while his other hand has moved to caress his ears and hair, and honestly, sometimes Blaine wonders if Kurt is capable of feeling more pleasure than he is or if he's just much more vocal about it because the noises he's making holy shit.

Kurt sighs when Blaine draws his jeans (he's not wearing any underwear and when Blaine's eyes widen at the sight Kurt laughs and pats his arm with a amused "try to fit anything in these jeans, they're fucking tight") down to his knees, raising his hips as the back of Blaine's hand brushes against Kurt's cock, and wow, his eyes are really dark, and Blaine is totally distracted by the way Kurt licks his lips.
"Are you sure?", Blaine asks, then, once his jeans and underwear are pooled around his ankles as well.
"I'm sure, you should really stop asking that. I'm not going to break, you know", Kurt says, his voice a bit breathless as he reaches up to kiss Blaine's (very much human) ear. Blaine nods.
"I just don't want to screw this up", he breathes, and Kurt runs his fingers through his hair and looks into his eyes in a way that says "I know". So, with a final "I love you"s Blaine presses his lips against Kurt's, making sure that their hips aren't connected, their tongues fighting almost lazily for dominance because they both know that Kurt has no intentions whatsoever to be in control tonight. So, when Kurt starts to whimper into Blaine's mouth, his nails digging into Blaine's back he pulls back, ignoring Kurt's protesting whine and trailing his lips down Kurt's neck, from the column of his throat to the dip beneath his collar bones, pausing to suck and nip at the places he knows Kurt is the most sensitive.
He pauses at his shoulder, his lips still touching the warm skin there but not really moving. Kurt whines then, though, high in his throat and sounding so needy, and can Blaine refuse when he asks so nicely? No, he can't, he decides before sinking his teeth into the flesh on the back of Kurt's neck.

The effect is immediate again, of course.

It seems like Kurt has lost all the self-control he usually has, his legs falling open and breath coming out in small gasps, and Jesus fucking Christ it's hot. Kurt has this look on his face, his eyes shut tightly while making helpless little sounds between the ragged breaths, and Blaine actually bites a little harder onto the skin there to stop himself from coming. It doesn't really work, though, because what it causes Kurt to do is to suck in a breath and spread his legs even wider, his chest heaving as he struggles to breathe, and Blaine closes his eyes and tries to steady his own breathing. But then Kurt does this helpless little thrusting motion with his hips, desperately trying to get some friction on his almost painful erection and it seems to snap Blaine back to the reality, where he has his beautiful, sexy boyfriend underneath him, begging to be fucked, and okay, fuck, that didn't do any good to the too-close-to-coming-without-any-contact-thing he's got going on there somewhere between their bodies. So, instead of facing the fact that he may come before he even gets inside of this whimpering boy he has underneath him, he actually lowers his hips onto Kurt's, gasping at the feeling and accidentally letting go of Kurt's neck with his teeth.

Kurt whines at the loss, but now Blaine finally realizes how awkward the angle was, and grimaces as he rubs at his stiff neck. He's quick to solve the problem though, now that he knows what it is, and gently rolls Kurt onto his stomach, ignoring his whines as his oversensitive erection rubs against the mattress in the process and Blaine kisses the back of his neck gently, before reaching behind of him to get the lube from where it is, abandoned on the sheets on the end of the bed.
It's probably the quickest preparation they've ever done, but who even could say no to a whining, whimpering Kurt Hummel as he writhes underneath him begging for another finger after only half a minute? So after four fingers and countless mewls Blaine lubes up his cock, wipes his hands on the sheets and sinks his teeth into Kurt's neck as he pushes inside.

Blaine thinks that he'll never get used to the way it feels to be inside of Kurt. The first time they did this he actually had spent a hour afterwards trying to wrap his mind around the fact that he had actually been inside of Kurt. Inside. He had been as close to him as humanly possible, and woah, okay, it had been a lot to take, even and maybe especially with said person sleeping soundly next to him with his arms wrapped around Blaine.
So, as he works his way into Kurt, carefully and slowly at first and struggling with the need to just thrust and take, biting at the back of his neck harder than he meant to, he shuts his eyes so tight he starts to see white stars, because he'll never get enough of the feeling of Kurt around him, on him, under him, tight and warm and so, so trusting with his mouth forming a perfect 'o' and little noises slipping from him as he tries to thrust back onto Blaine. He shushes him, though, pets his ears gently and smiles softly when Kurt relaxes a little at the touch and leans into it, completely distracted. It's not until Blaine starts pushing in again until Kurt tenses a bit again, little mewls starting to fall from his lips when he's far too gone to stop them, and this time Blaine doesn't try to distract him, because okay, whatever. The sounds he makes are amazing, anyway.

He stops once he's completely in, his hips snug against Kurt's ass and teeth still nipping at the flesh of the nape of Kurt's neck. It's like he's completely liquid underneath him, not moving and soft and submissive and God, Blaine loves him, and he can't quite wrap his head around the fact Kurt trusts him enough to let him do this, and Jesus Christ it feels amazing. Kurt seems to agree with him, trusting in his high-pitched mewls and the tiny ngh-sounds he keeps making, trying to give Blaine more neck to work with, and Blaine is more than happy to lick and suck and bite around the back of Kurt's neck while he waits for him to get used to the stretch, knowing that all the attention to his neck drives him absolutely crazy.

It doesn't take long until Kurt lets out a heavy sigh, and whimpers a little "move, please", just loud enough for Blaine to hear. He draws his hips back with his teeth still nipping at Kurt's neck, and Jesus fucking Christ remind him again why don't they do this all the time? It's amazing, and even thought they have done this so many times after the first time he's still so tight, and for a while Blaine is afraid that he's going to come already. Kurt starts to moan a bit louder, like he often does when he loses control of pretty much everything due to the relentless thrusts against his prostrate, and if Blaine thought that the noises Kurt made were amazing earlier, now they're just obscene and Blaine bites down harder again, not even noticing what he's doing because Kurt told him to go faster and as a dapper and good-mannered boy Blaine's not the one to turn down a direct request, so he settles on a slightly erratic rhythm that seems to do just fine, because Kurt's ears twitch approvingly and his tail starts to wiggle just a little.
"I love you so much", he says into Kurt's ear, even though it sounds more like a growl, and Kurt gives a full-body shudder at that. Blaine knows from experience that Kurt's ears are sensitive and he can't help but smirk against his skin before going back to his business.

Blaine shouldn't really be surprised when it happens, because fuck, it's so hot he feels like he might explode, but he still feels a bit disappointed when he feels the familiar tightening in his lower abdomen and he really tries to keep the rhythm up but loses the control of his body, but Kurt doesn't really seem to care, especially when Blaine reaches to take a hold of Kurt's cock, and it kind of surprises him when he can feel it pulse in his hand only after a few strokes. He must have been close for quite a while, Blaine thinks vaguely, moving further up his neck to get a better hold of it, and suddenly Kurt is gasping sharply, tensing underneath him and his tail straight like a arrow behind him as he comes, and holy fucking God, it's just on the edge of painful and Blaine sinks his teeth into Kurt's neck as deep as he dares and comes harder than he ever has.

Afterwards Blaine has his arms full of sleepy, purring Kurt, whose tail is fluttering a little behind him as he presses his face into Blaine's chest and sighs happily. Blaine can practically feel his heart swelling as he wraps his arms around the sleepy boy and presses a kiss on his still shower-wet hair.
"I love you", he says softly, not meaning to but doing it anyway because that's what he's been thinking about all night. Kurt's purring increases as he twists in Blaine's embrace to be able to look into his eyes.
"I love you too, silly", he says, bumping his nose against Blaine's softly and turning around again to make himself comfortable.

It's not until Kurt's purring fades and his breathing evens out that Blaine is able to fall asleep too. He buries his face into Kurt's neck, smiles a little at the scent of him and the confused little noise he makes in his sleep, and okay, what ever, no matter how great the sex is, this is the best thing ever, and when he lifts his head to press a kiss on Kurt's cheek and realizes that he's sleeping with a smile on his face he guesses that Kurt agrees with him.