What the actual shitting fuck. "What," Ren manages, but then he runs out of air and has to stop. He stares at the... the fucking apparition in front of him, his yellow eyes and the glowing lines tracing down his skin.

Yellow eyes. And the hallucinations, which began when he started to develop a Palace. There's only one logical conclusion. He sucks in a breath and manages to say, "Are you my Shadow?"