Let's pretend Kyle's mom doesn't know Cartman is the one with the needed kidney, for plot convenience.
Kyle lay very still in his bed and gazed at the ceiling. His eyes followed the lined patterns for a moment longer, then he sighed and closed his eyes. He had no strength, barely enough to talk. Sounds seemed too loud and his mouth was always dry. He had snapped out of his delirium though. For now, at least.
He heard his mom come back up the stairs, followed by a pair of footsteps he didn't recognise. Another doctor, maybe? Someone from school? His mom called to him, "Kyle, bubbe, one of your little friends is here to see you."
Kyle parted his eyes wearily and the room came slowly back into focus.
His mom's voice faded as she made her way back out. "I'll be downstairs, Eric. Don't be too long now. Kyle needs his rest."
Kyle stiffened. Eric. "Mom, no.." he called after her weakly. Cartman said nothing, only watched him. "Mom, wait, please don't.." He let what was left of his voice trail off. She had gone. He closed his eyes as Cartman approached his bedside. "What do you want, fat-ass? Come to gloat?"
Cartman pretended he hadn't heard. "How are you feeling, Kyle?"
Kyle cracked open his eyes. Cartman was leaning over him and smiling sweetly, his eyes gleaming. He didn't trust those eyes. "You can see how I'm feeling, dumb-ass. What do you want?"
Cartman smiled and ignored the question again. He spotted a still damp flannel on the bedside table and lifted it to Kyle's forehead.
"Cartman, what are you doing?"
"Just making you more comfortable," he replied sweetly, gently mopping his brow.
"Well, knock it off. It's creeping me out."
Cartman obediently removed the flannel, but without warning he replaced it with his hand, his fingers touching Kyle's hair. Kyle flinched. He didn't want to, but he couldn't help it. Cartman's grin widened.
"How much is your life worth to you, Kyle?" He asked silkily, caressing his hair.
Kyle craned his head away slightly and sneered at him. "So that's why you came, you sick fuck. Want do you want, money? All my computer games? And take your damn hand off my hair."
Cartman dragged his fingers through the curls slowly and deliberately. "You seem to have forgotten that I am the only one who can save you, Kyle. Me. You're mine. Your life is in my hands." His fingers tugged a lock of hair quite sharply for a moment, then gently petted it again. "If you want to live, perhaps you better speak to me with a little more respect."
Kyle said nothing.
"I've been thinking," he continued, stroking his hair thoughtfully. "I've decided I will accept an alternative price to the ten million dollars."
Kyle skipped a beat. For a moment he had forgotten what they were talking about. The hand in his hair was freaking him out. He couldn't let Cartman see that though. That was what he wanted. "Really," he responded dryly.
"Yes," Cartman answered seriously. He moved a little closer to Kyle. "If you want to live, Kyle, and you can't give me ten millions dollars, then you have to do something else for me." The hand in his hair disappeared. Cartman put his mouth to Kyle's ear and whispered.
"What? No!" He tried to shout, but it came out barely stronger than a whisper.
"Yes."
"No!"
"Yes, Kyle."
"I am notsucking your balls, you stupid fuck!" He tried to say more and went off into a coughing fit.
Cartman picked up the glass of water beside him and held it to Kyle, moving his free hand to the back of his neck to help him drink it. "I'm a reasonable guy, Kyle," he said smoothly, as Kyle drank. "I've no intention of making you do it now, when you're all weak and feeble. I can wait."
Kyle drained the glass, and Cartman placed it back on the table. "After you've had my kidney. After you've had the operation and recovered." He smiled angelically. What more can you want? The smile said.
"After I've recovered," Kyle repeated.
"Of course, Kyle, so that you know I'm not tricking you," he explained patiently. And so you're fully yourself and know what you're doing, he added silently.
Kyle squeezed his eyes shut. There was nothing else. "Okay," he whispered.
Cartman smiled in return. "Good, very good, Kyle."
He didn't like that. He wasn't Cartman's pet.
"I'll go to the hospital right now."
Kyle blinked up at him in surprise. "Now?"
"Of course, Kyle. I want you to get all better." He walked away but stopped in the doorway and turned back to face him. "Oh, and Kyle, I know you must have some little idea in your head of refusing to suck my balls once you have the kidney. Well, you can hang on to that little fantasy if it makes you feel better, but I give you my word; you will suck my balls, Kyle. You will." He left before Kyle could reply.
Kyle listened to him go down the stairs. "God damn it," he muttered to himself, and let his eyes flutter to a close. What an idiot. He bit his lip. A creepyidiot, though. What the hell was he trying to pull? He touched his hair where Cartman's hand had been and shivered slightly.
Update in a few days, a week tops, in which Cartman will be a bit more in character.