Ren started following him on the thirty-sixth day.
At first, Gray thought it was coincidence. The boy happened to be going the same direction, happened to need something from the same area, happened to appear wherever Gray was working. But by the third supply run, the pattern was undeniable. Ren was attaching himself like a shadow, silent and persistent, his dark eyes tracking every movement Gray made.
Gray didn't know what to do with that kind of attention. He'd never been someone people followed. He was the one who watched from corners, who noticed things others missed, who disappeared into the background when attention turned his way. But Ren didn't seem interested in the background. He was interested in Gray.
"Ask," Gray said finally, on the fourth day, as they moved through a collapsed department store. The shelves had toppled like dominoes, creating a maze of rusted metal and scattered merchandise. "You've been staring at me for three days. Whatever you want to know, just ask."
Ren's footsteps faltered, then resumed. "I'm not trying to be annoying."
"You're not annoying. You're curious." Gray ducked under a fallen beam, his eyes scanning the shadows for movement. "There's a difference."
The boy was quiet for a moment, picking his way through the debris with surprising grace. His small frame slipped through gaps that would have trapped an adult, his feet finding purchase on unstable surfaces as if he'd been born to navigate ruins.
"The patterns," Ren said finally. "The things you see. How do you know what they mean?"
"I don't."
"But you act on them. You move different when you see something. You tense up before the danger comes."
Gray stopped, turning to look at the boy. Ren's face was earnest, his brow furrowed with genuine confusion. He wasn't asking for a lecture. He was asking for survival knowledge, the kind that could keep him alive when the world turned hostile.
"Sometimes," Gray said slowly, "I see threads. Lines of light that connect things. They move in patterns, and when something is wrong, the patterns change. I don't always know what the changes mean. I just know they mean something."
"Can you teach me?"
The question was simple, but it carried weight. Gray looked at this boy, this child who had survived weeks alone in a hospital while things hunted the halls, who had watched his parents taken and his sister left behind, who had emerged from that nightmare with his spirit intact and his mind hungry for understanding.
"I can try," Gray said.
He started with the basics. Not the patterns themselves, those were too personal, too tied to whatever strange ability had awakened in him after the collapse. But the skills that came from observation, from learning to read the world without needing to see its hidden threads.
They moved through the ruins together, Gray pointing out what he'd learned through trial and error. The way dust settled differently in areas where hollows had passed. The subtle discoloration on walls where the wrong-color light had touched too long. The sound of structural weakness, a groan in the concrete that preceded collapse by seconds.
"Feel the air," Gray said, pausing at an intersection of fallen corridors. "What do you notice?"
Ren closed his eyes, his face tilted upward. His chest rose and fell with slow, deliberate breaths. "It's... colder. Coming from the left."
"Good. What else?"
"There's a smell. Like rust, but sweeter."
"Blood. Old blood." Gray's jaw tightened. "That direction leads somewhere something died. We go right."
The boy absorbed every lesson with fierce intensity. He asked questions that surprised Gray, questions about why hollows avoided certain areas, about whether the patterns could be predicted, about whether the abilities some people had developed could be learned or were only born. Gray answered what he could, admitted ignorance when he couldn't, and found himself thinking about problems he'd avoided considering.
On the fifth day, they found a pharmacy that hadn't been completely looted. The front had been smashed, the obvious shelves stripped clean, but Gray's pattern-sight caught something the looters had missed. A door behind the counter, hidden by debris, that led to a storage room still stocked with supplies.
"How did you know?" Ren asked, watching Gray pull bandages and antibiotics from the shelves.
"The threads were different. They moved around the door instead of through it."
"Can I see them? If I look hard enough?"
Gray turned to face the boy, really looking at him with his sight active. The faint luminescence he'd noticed before was still there, a soft glow in Ren's chest that pulsed with his heartbeat. Latent sensitivity. The same thing that had drawn the hunters to his parents.
"Maybe," Gray said carefully. "It's not about looking harder. It's about... letting go. Stopping the part of your brain that tells you what you're seeing can't be real."
Ren nodded as if this made sense, as if Gray had given him a key to a door he'd been searching for his entire life.
They returned to the warehouse as the sun was setting, their packs heavy with supplies. Mina met them at the door, her eyes moving from Gray to Ren and back again, a question forming on her lips that she didn't voice. She took the supplies without comment, her fingers brushing Gray's hand in a moment of silent acknowledgment.
Over the following days, the pattern solidified. Gray would wake, find Ren waiting, and they would head out together. Sometimes Elias watched them go, his expression unreadable. Sometimes Mina pressed food into their hands and reminded them to be careful. But mostly, they moved through the ruins as a pair, the man who saw too much and the boy who wanted to understand.
Gray found himself teaching without meaning to. Not just survival skills, but ways of thinking. How to question assumptions. How to look at a situation from multiple angles. How to recognize when something felt wrong even if he couldn't explain why.
"You're good at this," Mina said one evening, after Ren had gone to sleep. She'd found Gray at his usual spot by the western window, the position that had become his default in the weeks since the argument with Elias.
"At what?"
"Being a teacher. Being a..." She hesitated, searching for the word. "A brother."
The word landed heavily. Gray turned to look at her, seeing the softness in her expression, the way she was watching him as if he'd done something remarkable without realizing it.
"He's not my brother."
"No. But you're treating him like one." She smiled, a small, tired expression. "You're teaching him to survive. You're showing him he matters. That's what brothers do."
Gray looked across the warehouse floor to where Ren slept, a small figure curled in a nest of blankets, his breathing slow and even. Something in his chest shifted, a softening he hadn't expected.
He'd never had a brother. Never had anyone who looked up to him, who followed him into danger and trusted him to bring them back out. But looking at Ren, seeing the way the boy had begun to hold himself with more confidence, the way he'd started asking questions instead of just accepting the world as it was, Gray thought maybe he understood why Mina cared so much about protecting people.
It wasn't just about survival. It was about giving someone the chance to become more than the world had tried to make them.
"He's a quick learner," Gray said quietly. "Faster than I was."
"Then he's lucky to have you." Mina reached out, her hand finding his in the darkness. "And you're lucky to have him."
Gray wasn't sure about luck. He wasn't sure about much anymore. But as he watched Ren sleep, as he felt Mina's warmth beside him, he thought maybe there were worse things than having people to care about.
Maybe that was the point of surviving at all.