Just after dusk, Karkat steps outside and headed for the lake, turning a deaf ear on his custodian's warning screeches. The stars and moons overhead glow steadily down, lighting his way through the shadowed trees. These excursions to the lake started when he stood in front of the bathroom mirror one pre-dawn night, giving his teeth a routine brushing after dinner. He spat out some minty gobs of fangpaste and went to rinse his mouth out with water. When he turned the water tap into his waiting maw, the terribly unreliable plumbing surged with all the fury of a seasonal hurricane, splashing all over his face, forcing water down his gullet, and all but drowning him in his kitchen sink.
And he might've drowned.
If he hadn't been a mutant freak.
It was nothing he couldn't have forseen. His fiery, cull-red blood was only the worst of his imperfect genetic manifestations. His growth had always been embarrassingly stunted in comparison to like-aged trolls, his horns had always been short and nubby and really pathetic excuses for "horns" at all, his fangs were intermittently blunt as a rustblood's and razor-sharp like royalty (plus crooked as hell to boot), and his capacity for channeling psychic energy had tested out as officially lowest on record. Absolutely zero. They didn't even think it was possible; even the most psychically inept scored at least something.
That night in the bathroom, Karkat's throat closed up somewhere he wasn't aware was physically capable of closing up, and his neck stung sharply with pain, tensing up as torrents of water attempted to crusade its way down to his toes, and then with a panicked gasp-spasm, Karkat finally got out of the way of the faucet and wrestled with the handle until the water was subdued.
A loud, furious, painful sigh, and he winced, touching his neck just under the jaw. Another sharp sting of pain. His fingers felt hot and slippery and when he pulled them away, they were slathered in that awful color he so abhorred. His eyes met his reflection in the mirror, and he hastily wiped some spray away with one sleeve, craning his neck and eyes to see what the fuck had gone wrong with him this time.
Three bright-red slits on each side, starting at the jawline and ending halfway to his collarbone, blood flowing freely from the gashes, as though a clawed beast had just attempted to decapitate him. Then his throat closed deep inside, opened, closed, opened, closed, and he took deep, shaky breaths when he could, closing his eyes and focusing on keeping his dinner down.
When the blood stopped flowing and his neck stopped hurting some days later, he dared to take another look in the reflection plate.
The slits were still there, and when he stretched his neck in any way, strips of his blood color became clearly visible. Taking the most calming breaths he could muster, he touched the slits gently with his fingers, and though they didn't hurt, they were extremely sensitive. Slick and almost feathery to the touch.
He went down to the food preparation block, acquired a large pot, and carried it back up to the ablution chamber. His custodian clacked curiously at him, but Karkat paid him no mind.
He filled the pot with water, tipped his face to the ceiling, and poured a steady, heavy stream of water down his gullet. It didn't go well. The water went straight down the wind chute and he damn near drowned himself, and spent about ten minutes coughing water out of his lungs. And then he filled the pot to try again. Second time around, his throat closed up in that weird place, and then the water just poured out through the slits in his neck. He slowly poured all the water out of the pot, letting it pass through the lacerations, not stopping to take a breath into his lungs.
When he was done, his clothes were soaked through. He set the pot aside, sat down on the wet tile, and put his face in his arms.
Fucking. Gills.
Trolls and their lusi often share unusual abilities and horn shape, if applicable. Aradia could leap like a fucking kangaroo, Tavros liked to dream that he'd pupate wings (but that was probably total bullcrap), Sollux's Biclopsdad had to be somehow indicative of the weird duality shit, Nepeta's sense of smell was easily comparable to a meowbeast's, Terezi was predisposed to scent/taste-to-color synesthesia like her blind dragon lusus, Vriska, well, Karkat wouldn't be surprised if her bite was literally venomous (not to mention the whole eight-eyes thing), Equius could lift a house with a pinky and everyone knows centaurs are the most powerful lusi, Gamzee was as coherent as a goat, Eridan and Feferi were seadwellers, obviously, and Feferi probably had some lifespan-culling psychic abilities, if her ancestor and lusus was anything to go by.
And then there's Karkat.
A mutant land dweller, with fucking gills.
How is that fair, at all? It was going to be turtlenecks from there on out, because scarvves were a definite HELL NO.
He should just be happy it wasn't pincers.
When Karkat gets to the lake he takes off his shoes, socks, sweater, shirt. Hides them under some bushes. He looks at the reflective surface of the water, breathes the air out of his lungs, and touches the side of his neck briefly before diving in. His throat closes down in his esophagus somewhere, and he takes gulp after gulp of water as he swims down to the bottom, where its dark, and silent, and the thin light shed by the stars is all the light in the world.
He lays on the bottom, stares up at the shimmering surface, lets his limbs float gently and his hair sway sluggishly around him. Down here, everything's slower, emptier, quieter than the hectic, nerve-wracking violence above. Down here, he's halfway suspended in death, breathing water like he's not one of the damned. Down here, he's peaceful.
When dawn draws near he swims to the surface and as soon as his face breaks the water and his lungs cough and gasp to catch a hold on the thin, turbulent air, Karkat Vantas is once again a mutant, a freak, horrified at what he is and how his body is illegal on at least six hundred different levels. He touches the side of his neck and steps clear of the water, shaking with cold, drenched and limp and terrified.
He promises himself that this was the last time; he'll never go back.
But he always does.