Admittedly, the thing that stopped him through that blind red color in his vision was Kytana's cough. Something just grabbed him all of the sudden from somewhere in his gut and it hurt, it twisted. It was...concern? He stared at his Master's face even as his own looked so marred with pain and struggle. Darkness shrouded him, swallowed him; so little light was left.
A moment hung in the air as Kylo Ren stared back at Kytana before his gaze flickered to Luke. Another time. Another time he would finish his task. So, in finality, he said to his uncle, "go." His voice was so cold and filled with disgust. It was likely he hadn't heard a thing the man said, or perhaps he simply didn't want to believe it. Believe that he was being used even as he knew deep down he was. For emphasis he turned from Luke, not showing him his back so much as giving him that reprieve to run before he might be sparked to attack once more, and strode toward Kytana's side. Though his saber hung out and open at his hand he did not use it against her.
"Are you ill?" he asked and the appearance on his face, the way the muscles moved, Kylo Ren couldn't say he remembered making that kind of face in a long time. Maybe there was still some light left, dim as it may be.