Karkat was sure John had cheated. Unfortunately he couldn't prove it. The troll knew Egbert had cheated because he had never lost a bet to the boy before. This was because Karkat never took a bet with John he wasn't sure he would win. Sometimes they were inconsequential, others not so much. Smaller ones were usually for some amount of money, which wasn't a big deal. The more elaborate bets though ended with things like Egbert dressing in drag for 2 days or trying to convince Strider that he was in love with him. That had the unintended bonus of getting to watch Terezi beat John up as well as enjoying the boy's suffering and repeated insistence afterwards that he is not a homosexual!
But this time, somehow, John had won the bet. And unfortunately for Karkat, the winner earned the privilege of bleaching the other's hair and dying it any color they wanted. Karkat had planned on bright green for John. It would extra piss him off, since he really preferred blue. But Karkat had lost, and so rather than revelling in John's green misfortune, he was here, in a chair, with a trash bag with a hole in the middle over his shoulders in case Egbert made a mess.
They had already bleached his hair. A blond Karkat, they both decided, is one of the weirdest things they have ever seen, and that's saying something! Now John was preparing the dye. He had yet to tell Karkat what color he had chosen. Karkat was betting on purple, since it would add injury to insult with a subtle jab at the hemospectrum.
"Oh! Almost forgot!" John exclaimed. Karkat decided that was not a good thing. They he heard behind his head the sound of John ripping off a piece of masking tape. OH SHIT. He had forgotten that. When they bleached his hair they had almost bleached his horns, Karkat had splotches on his hands from wiping the bleach off, despite the fact that he had washed his hands immediately after. John had come up with the solution of wrapping Karkat's nubby horns in masking tape and hoping the dye didn't bleed through. Karkat's problem was John could see the top of his head way better than he could, and therefore it made no sense to let Karkat wrap his own horns. SHIT.
John was digging around in his hair, trying to find his scalp. "You have too much hair, Karkat."
Karkat didn't answer, he was bracing himself. Finally John got down to his scalp and pressed the tape to the base of his horn. Karkat twitched, hoping John wouldn't notice. John began carefully winding tape around the yellow and orange nub while Karkat fought to stay still and quiet. All trolls' horns are sensitive, but Karkat's more than most. John finished wrapping the first one and ran his hand over the tape to make sure it's stuck tight. Karkat squeaked. John noticed.
"Are your horns sensitive Karkat?"
Karkat hissed angrily. John snickered and lightly stroked the troll's other horn. Karkat shuddered involuntarily. He couldn't see Egbert, but he knew the boy would have an insufferably grin on his stupid face. John dragged a nail over Karkat's horn and he gasped.
"STOP IT EGBERT! I MEAN IT!"
Another snicker. Karkat felt his hand leave his head and relaxed slightly. Only to cry out as the stupid boy licked his horn. "WHAT THE FUCK EGBERT!"
Blindly he lashed out behind him and surprisingly managed to hit the human, but not hard enough to hurt. John just snickered again and grabbed the tape. "I HATE YOU," Karkat muttered.
Next John turned to the dye. He didn't really know what he was doing, but he had a brush which he was using to paint the dye onto Karkat's hair. After a bit he gave up on that and started using his gloved hands. Karkat scowled. John "I am not a homosexual" Egbert was making every effort to touch his horns as much as possible, and laughing at the troll's reactions. Even naive Egbert could clearly see the way his touching was affecting the troll. The feel of the boy's hands in his hair wasn't helping either.
Finally, after what seemed like ages, John declared that he was finished, having run out of dye. He instructed the troll to stay put and wait for the dye to set while he bustled about cleaning up. Eventually he let Karkat wash the extra dye out of his hair. Karkat had to endure John mockingly peeling the tape from his horns with agonizing slowness. He put his hands over Karkat's eyes and pushed him in the direction of the mirror. He whipped his hands away and Karkat let out a strangled squawk. John had not dyed his hair purple like he had predicted, though he had taken a jab at the hemospectrum. Karkat's hair was fire engine red. It clashed horribly with the color of his horns.
As soon as he had removed his hands, John ran. Karkat took off after him.
"I AM GOING TO FUCKING KILL YOU JOHN EGBERT! I FUCKING HATE YOU! OF ALL THE COLORS YOU COULD PICK YOU HAD TO PICK FUCKING RED? WHAT THE FUCK IS WRONG WITH YOU? YOU ASSHOLE! I AM GOING TO FUCKING STRANGLE YOU WHEN I CATCH YOU!"
John did the windy thing to get away from the angry troll.
Eventually Karkat calmed down, until John snuck up behind him and grabbed his horns. Unprepared Karkat's knees buckled and he collapsed. He got to his feet and turned before John could get away. He jumped the taller boy, shoving him to the ground and kissing him. John's hands flailed about for a moment before he gave up and kissed the troll back, winding his hands into ridiculous red hair.
Karkat thought to himself later that maybe loosing bets might not be so bad. But he was still dying John's hair a weird color as soon as he got the chance.