Okay, I gotta explain my horns headcanon for y'all. It's not important to read though if you don't care about the mechanics, so feel free to skip it.
I think of horns as being a sensory organ. They'd be used to pick up certain vibrations or such so as to be aware of their environment, or alternatively to aid in navigating very dark places (such as in the caverns they're hatched in). I imagine that nearer the tips they'd be thicker/less touch-sensitive to prevent issues that might otherwise be caused by bumping into stuff or whatever, and that closer to the base it'd be a little more malleable and sensitive. Having an important sensory organ in a sort of dumb place, trolls have evolved so that if a lot of pressure is put on the horns (especially closer to the base), as if threatening to break them, that there would be a release of hormones and chemicals to make them go slack. This would prevent them from resisting the pressure and reduce the chance of breaking the horns. Think something similar to when you pick up a kitten by the scruff of the neck.

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"SOLLUX!"

Oh wow holy FUCK, If there is anything you absolutely do NOT need right now, it is Karkat Vantas screaming. Were you to compose a Top Ten list of things you could really, really do without at the moment, Karkat's Screaming would take up every slot three and under. If you weren't counting the conditions that have made the yelling utterly and wholly intolerable, then Karkat's Screaming would take the top two as well; It's pretty much the worst possible thing for you to have to deal with on top of your already astronomical levels of pain.

You have it on good authority that there is an athletic competition being hosted inside your thinkpan involving lumberjacks, active construction sites, and an enthusiastic crowd made up of The Voices of Soon-To-Be Worm Chow. That authority is your mind-searing agony, and as far as you care that's the highest authority there is right now. Everything between your shoulders and your horns aches; Your muscles are twisted into tight burning knots, your eyes are so light-sensitive that you can scarcely stand to open them, you can feel your pulse throbbing in your teeth for fuck's sake. And your head? You're almost positive that there aren't even words in your vocabulary to do the pounding waves of torture justice. Suffice it to say that, if given the choice between this and gnawing off your own hands, you well might have to learn how to navigate a keyboard with your toes.

So, yeah; The universe would be doing you a huge solid if Karkat would shut his face and happen to wander conveniently away from your little hideout without realizing that you're here.

Sadly, it's not much of a hideout. It is not, in fact, a hideout at all, but rather an arguably public venue that everybody in this hellhole knows about, and right now you are regretting your life choices. Yes, it is hands-down the most comfortable place you could have tucked away: A heap of plush scalemates, soft animal pelts, and various articles of (thankfully clean) clothing that has congealed in the back corner of a small, dark storage block not too far off from the lab. It is also, as previously mentioned, a spot everyone is aware of, so it's pretty high on the Places To Search If You're Looking For Someone checklist. You probably would have been better off ducking into a cleansing supplies cubby- No one would have found you there, at least.

The universe is unfortunately not taking requests at this time, and you brace your hands on your temples in preparation when you hear Karkat's thunderous approach. You hadn't even had the sense to burrow into the pile when you took refuge here, pain-addled as you are, so you're smack dab in the middle and right on top, curled on your (red) side where you are impossible to actually miss. You are coming to think that the universe may be deep in the black throes for you and is doing its best to solicit your hatred by screwing you over at almost every possible turn.

Sure enough, Karkat spots you plain as moonlight and makes a beeline for the pile, his fists clenched at his sides and his face in a scowl. You're already wincing.

"Hey, shitbag, I have been scowering this rock for your sorry ass for-"

"KK. For the love of fuck, not so loud," you choke out, pressing the heels of your hands hard against your temples, and it's very nearly a sob. It stops him in both his literal and figurative tracks. His aggravated expression is instantly replaced by one that is roughly 50% concern, 20% reluctance to put his anger on pause long enough to find out what your major malfunction is, and 30% Oh Shit Wait What Should I Do. That is not the important part, though; The important part is that the way you spoke was apparently pathetic enough that he's temporarily shocked into silence.

He stands there near the pile awkwardly for a moment and gives you a quick once-over, presumably to look for any obvious signs of physical damage. You think that he must not be operating at full brain capacity if he can't immediately surmise what you're suffering from, but you can't ever really count on him to be all there when he's presented with something that distresses him emotionally. You suppose that finding his quasi-romantic partner / best friend miserably writhing around in almost crippling agony is probably something that distresses him emotionally.

"… What's wrong with you?" he asks, blessedly at a much more migraine-friendly volume, and in a tone that is trying very pointedly not to sound fretful.

"Headache," you tell him despondently, voice a little rough around the edges.

"Oh..."

There is another blissful (well, fractionally less terrible) stretch of noiselessness, broken only by some discomforted fidgeting on Karkat's part. You squeeze your eyes closed again, under the impression that you've given him an adequate enough reason to leave you alone; You're by no stretch of the imagination a pleasure to be around when your migraines hit, and it's not a secret that they can, in fact, be detrimental to other people's health on occasion. As a general rule, you're given a wide breadth when you're in severe pain because it makes you even more likely to fly off the handle over stupid shit than you usually are.

Apparently Karkat's sense of self preservation has gone the way of his missing brain function. Instead of turning around and walking right back out of the room like any half-sane person would, he spends a minute or two dawdling, then crosses the remainder of the gap between him and yourself to sit in the pile just next to where you're laying. You crack open one blue gander bulb to give him the best glare you can muster, but he just purses his lips and holds eye contact in challenge. It's not long at all before you decide that you don't have nearly enough fucks to give and close your eye again. He's not being his usual bothersome self, or at least he isn't yet, so you guess there's no real reason to exacerbate your headache in a likely vain attempt to get him to leave. Might as well just let him alone.

Neither of you do or say anything for some while- Unless the small noises of discomfort you make intermittently count- and even though it's not doing you any particular good, it is sort of nice to have company while you're feeling like shit, you guess. Specifically, company you don't have to worry will try to assault you one way or another while you're in a vulnerable position.

Ultimately though, your occasional grunts and whines become a Thing That Is No Longer Tolerable for Karkat; After one that comes close to being an honest to god whimper, he sighs, loud and uneasy.

"Did you try taking that synthesized pain remedy sap we found in the medical block?"

"No, of courthe not. Why would that thought even occur to me? It'th not like it'th the most obviouth firtht courthe of action to anyone with a functioning brain or anything."

"Fuck you twice sideways. What about a cup of steeped plant-matter? I'm sure Kanaya would make some if we put in a request for it."

"That fetid thwill ithn't good for anything but churning my digethtive thack."

"I think if there's so much as half a chance that it could help, it'd be well worth the effort you'd have to expend to stop being a huffy pantywaste of a wiggler long enough to choke it down."

"Well there ithn't half a chance and I'm not going to drink it."

"Like you would fucking know whether or not it could work."

"I do."

"No you don't, you're just being a stubborn whiney bulgebag."

"Dude, if a thyrupy death-flavored chemical cocktail dethigned thpecifically to block pain can't do the job, then I'm pretty sure thome foliage in hot water ithn't going to cut it."

"… Alright, fine, I'll concede to that point. Have you-"

"KK, thtop. Would you jutht be quiet?"

"Are you seriously so resigned to the physical and mental anguish you're apparently dealing with here that you won't even consider that there might be a way to alleviate some of it? That's fucking pathetic, Captor. I'm not sure if I can associate with someone this deplorable, I might have to void our contract of friendship."

"No, really; Firmly secure your squawk blister in the muted position," you flop a hand over to the side and swat him on the thigh.

There is a wonderful lapse back into silence...

For maybe all of a whole three minutes.

"… My future self is probably cursing me as we speak for even asking, but is there anything I can do?"

"You can close your horrendous god damn mouth, you inthufferable little shit," you hiss at him, full of venom.

He looks taken aback for just a second at the outburst, but recovers quickly and delivers a pretty impressive sneer. "Wow, I don't think I've ever been proven right so fast in my life. Congratulations, nookwhiff, you've set a new Asshole Record."

"Which part of 'shut the fuck up' are you not underthtanding."

The rational part of your brain, buried under at least seven different layers of frustration, pain and aggravation, is surprised when Karkat neither storms out nor starts yelling- He just grits his teeth hard and quiets. That same part is also dimly aware that you'll feel like shit later about snapping at him for wanting to help you. At the forefront of your mind, however, you are much more focused on the fact that he's stopped talking, effectively dropping the external noise levels to zero. That is a really, really nice number for the external noise levels to be, and your aching pan thanks you for the small amount of difference it makes.

You snuggle a little deeper into the soft pile. Apparently Karkat finds this to be an appealing concept and lays down himself, curling on his side a small ways in front of you. Though you can't see him right now, you can feel his eyes on you. He's stubborn like a crotchety old mule, so you know that he's probably still trying to come up with a trick to allay your ailments, but you couldn't give half a shit less so long as he's not doing it out loud.

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-::{( ~ . : '*' : . ~ )}::-
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After a bit, when you've almost managed a restless doze, you feel fingers brushing over your cheekbone and your eyes snap open. Karkat's somehow shuffled up closer without you noticing and his face isn't very far from yours. You give him an unamused glare, but he's not looking at you anyway; His gaze is fixed somewhere over your head, and his brows are furrowed, the way they are when he's trying to figure out the solution to a problem. Is this bulgemonger trying to pet you without even realizing it or something?

"… KK."

His eyes fall to meet yours, and he holds the visual contact. He's clearly still mentally preoccupied by whatever he was thinking about, though, and he doesn't say anything. What he does do is pull off your glasses and toss them higher up the pile, then settle his offending hand on the side of your head so he can rub tight little circles against your temple with his thumb.

… Fine. It isn't going to actually help your migraine, but if it'll make him feel better and keep him from fussing like a cluckbeast lusus again, then whatever.

When you fail to pitch a ragefit about the action, Karkat takes it as a go-ahead. He shifts his weight so he can slide his other hand between your head and the rumpled tshirt it's resting on, and applies the rubbing motion to your red-side temple as well. While it does nothing for your pain, it's still sort of soothing. It also somewhat placates that half-smothered section of your mind that knows you'll feel guilty later for having been needlessly testy with him; He can't be too upset about it if he's still got any interest in initiating nonviolent contact. You decide to further assuage the vague nagging by tilting your head a bit and pressing a kiss to one of Karkat's wrists in half-assed apology.

You settle into a… Well, not quite relaxed state, but certainly less tense. The feel of Karkat's thumbs in their consistent, repetitive motion gives you something to focus on other than the heavy pounding that's making your brain rattle inside your pan. His weight nearby eases you, and his body heat is cozy and mollifying. The combination of all these things makes your headache marginally less unbearable, and overall leaves you feeling a little bit lulled.

Until there's suddenly a set of fingers clamped hard around the bases of your blue-side horns.

Your built-in reaction is to be very fucking alarmed holyshitohgodohno, and you have just enough time to yelp rather hilariously before the flood of various hormones hits your system like a freight train. It is a very large freight train that comes barreling out of the blue and completely bowls you over, leaving you almost entirely limp amidst the wreckage that is your higher physical functions.

"KK, what the fuck?" you ask, voice thin and airy for the way your body is trying to tell everything non-vital to kick on the brakes. You want to twist your fingers tightly into the front of his shirt for the sense of being grounded, but all you can manage is a very weak grasp on the fabric. You're pretty sure you're going to have to gut your best friend with a rounded eating utensil when you're in full control of your limbs again.

"Shoosh. You're fine, Captor, don't be a grub," he reassures calmly to try and remind your brain that he is not, in fact, any actual danger to you. If you'd seen it coming (and weren't in such a pissy mood), you probably wouldn't have been especially bothered by Karkat grabbing at your horns; It's not really uncommon to let people you trust gently stimulate them in order to send tiny trickles of the chemicals that, in small doses, can be relaxing and pleasant.

This, however, is not gentle stimulation, this is a veritable death grip that had been thrust upon you without warning, and your instincts consider that a serious threat, logic or no.

The reflexive panic can be dealt with in the same way all panic can, though- By establishing an atmosphere of comfort and safety. That's what Karkat goes for; He slides his free hand under your neck and around your shoulders, then uses the leverage to roll you over with him just a bit so that he's lying on his back with you tucked into his side, your cheek resting on his chest. Once you're situated, he yanks one of the larger animal pelts out of the heap from somewhere behind your back and drags it to completely cover the both of you, with a little difficulty for needing to do it one-handed, which gives a vague impression of being securely huddled inside a cocoon.

When he's satisfied that he's created a suitably calming environment (and it admittedly is, for all that the approach is simple), he uses his free hand to smooth your hair and churrs a soft conciliatory noise that sounds a little strange coming from him.

You sigh in relief when he loosens the hold on your horns, and after a few seconds you're less utterly useless; You still can't move around very much or quickly, but at least you can speak properly again. "Wath that really fucking nethethary?" you thump a loosely curled fist against his sternum in reprimand. "What are you trying to accomplish here, shithead? If you did that jutht to keep me from fighting you on inappropriately timed Happy Thstarshine Thnuggle Hour, tho help me, I will murder you in your thleep."

"Please. Like I'm really so inclined to get all disgusting and cuddly while you're being a pain in my ass that I'd put that much effort into it. Not that it was actually difficult, but the fact remains that it would not by any measure have been worth it," he snorts.

"Then what are you even trying to do? Give me a heart attack? Render me immobile tho you can call for backup and force me to drink that nathty leaf water after all?"

"I thought it might help- You know, with the headache and the knots you probably have from holding yourself rigid like an idiot," he shrugs the shoulder you aren't half-laying on. "Override your system with chemicals that might block pain to a certain extent, or can at least thoroughly distract you, and force your muscles to unclench. Did it work?"

You take a moment to assess the state of your suffering to discover that there has, in fact, been a fairly marked improvement. It's still awful—Your head continues to throb relentlessly, your neck and shoulders still burn—But it is several degrees less agonizing, like the sharp edges have been filed down. "… Oh. Yeah, I gueth it did help a little. Congratth on proving yourthelf not to be completely incompetent in all thingth ever, it mutht be really exthiting for you," you snark good-naturedly and nudge at Karkat's jaw with your nose.

"Holy fuck, Sollux, settle down," you can practically hear him rolling his eyes, and he takes up fiddling idly with locks of your hair. "No need to drown me in your gratitude or anything. I hardly deserve such high praises."

"Don't be tho modetht, KK, it'th the leatht I could do. I'm not sure how I'll ever repay you for the great thervithe you've done all of trollkind by not being ath unfailingly inept ath we all thought you were."

"You could start by groveling at my feet and begging forgiveness on behalf of your incredible capacity to be an atrocious asshole at every available opportunity."

"Oh, of courthe. Let me do it in writing though, tho you can frame it. It'll be hand-printed in gold calligraphy on the finetht cholerbear-thkin parchment, and it will read: My darling KK, pleathe do not hethitate to eat my nook," you plant a pair of kisses under his chin. "But thtill, thankth for making me leth mitherable."