The part of Sam's brain that still demanded logic, even in the face of everything he'd seen in his life, was completely convinced that Clark had to be joking. But when those wide, innocent green eyes kept staring up at Sam intently, waiting for his reaction with fear and trembling, he knew Clark wasn't trying to pull a prank.

Still, there had to be some kind of mistake. Minutes ago, Clark had believed a gust of wind would be a compelling cover story for whatever had knocked out Sam and Dean and Lex. Clark was a confused ten-year-old, blaming himself for something that couldn't possibly be his fault. That was all this was.

Sam shook his head. "No, Clark. You didn't make that trail."

"I did!"

"I know you were there, but—"

"I didn't kill anyone, but I did make the trail. I have . . . powers. You have to believe me."

Sam raised an eyebrow. "Powers? What kind of powers?"

"Speed and strength. And . . . something my dad calls invulnerability, but I think that's part of the strength."

"Clark—"

"Look." Clark sped from one side of the loft to the other, then back again.

Real gusts of wind hit Sam each time Clark passed him, but it felt more like he'd had the wind knocked out of him. Sam had seen a lot of strange things in his life, but this was something else entirely. When Clark stopped running, Sam almost couldn't believe what he had just seen. Clark looked so normal.

"And look!" Clark went over to the hay bales, stacked up three on top of each other, and held the entire stack of his head. His arms didn't even shake with the exertion—it was as though they weighed nothing. He gently placed the hay bales back down. "Now do you believe me?"

"I—yes, of course I . . ." Sam took a step back, adrenaline pumping through his veins.

Clark frowned. "Are you—are you scared of me?"

"No, no, I just . . ." Sam swallowed. All his life, it had been drilled into him that anything supernatural was to be feared. To be killed, even. Sam was going to have to change those instincts, but it wouldn't be easy. Sam didn't want to make Clark feel rejected, but Clark had been honest with him—he owed Clark the same. "A little. But you're my friend. You're, like, the little brother I never had. I know you wouldn't hurt me."

"I've never hurt anyone. I left the trail, but I didn't kill those people!"

"I believe you," Sam said. Looking at the wide innocence of Clark's eyes, it was impossible not to.

Clark cringed. "Are you going to tell Dean about my powers?"

Sam took a deep breath. Dean would kill him if he ever found out that Sam was keeping this secret from him, but Sam wasn't worried for himself—he really had no idea what Dean would say about Clark. Worst case, he'd think they needed to find a way to kill Clark. Even in the best case, Dean would almost definitely insist they needed to tell Dad, and their dad would be a lot less understanding than they were. Even if Dad didn't try to hurt Clark, he'd still probably come here and drill Clark and his parents with questions and threats.

Sam didn't want to have to try to deal with this himself. He thought about trying to convince Clark to tell Lex. Lex was closer to Clark, and Sam was absolutely certain he wouldn't want to hurt him, but Sam also just didn't know Lex very well. Sam also didn't like the idea of Dean being the odd one out while the other three all kept secrets from him.

It didn't matter what Sam thought was best, though. He had sworn not to tell anyone, and he was going to keep that promise whether it was a good idea or not. Clark had just entrusted him with something enormous. Sam didn't have the heart to break that trust. He didn't have the right.

"I'm not going to tell anyone," Sam said. "But . . . they're already suspicious of you. That gust of wind story made no sense."

"I know." Clark's cheeks turned pink.

"Can you tell me what really happened? How did you leave the trail?"

Clark swallowed and rubbed at his face. "A few days ago, I was taking a walk after doing some chores, and I found a dead body. I got scared and ran back to the house—I'm not usually supposed to run at full speed outside of our property, and if I do, I'm supposed to be careful to be light on my feet. But after seeing the body, I got scared and forgot."

"And that's how you left the trail."

"Yeah."

"So whatever killed those people . . ." Sam shook his head. "It didn't leave a trail at all."

Clark shrugged. "Maybe it did, but my trail was more distracting."

Sam let his breath out. This was going to be a tough one to explain to Dean. "Okay. That was the other day. So what happened just now, while we were doing recon?"

"Um . . ." Clark winced. "I don't want you to be upset."

"I won't be upset if you tell me the truth. I promise."

"That's what my dad always says," Clark grumbled.

Sam knew the feeling—his dad never kept the promise not to get angry, either. "Hey," Sam said softly. "I'm not your dad. I'm just trying to help you. I promise I won't get upset with you."

Clark squeezed his eyes shut for a moment, then he looked back up at Sam. "You three were all talking and laughing, and I heard something coming. I ran after it while you weren't looking, and I saw this monster coming toward you."

"That's what knocked us out?"

"Uh . . . no . . ." Clark started wringing his hands.

"Then what?"

"I didn't want you guys to get hurt. I'm a lot stronger than any of you, and you didn't have any weapons, but I couldn't use my powers in front of you, or you'd know my secret. So . . . I kind of . . . maybe . . ."

"You knocked us out?" Sam yelled.

Clark cringed. "You said you wouldn't be mad if I told the truth!"

He had promised. Sam forced himself to take deep breaths, thinking everything over carefully. Clark was just a kid. Faced with the choice of letting his friends get killed by a monster, or revealing a secret that his parents had forbidden him to reveal, he'd made a snap decision. If he was guilty of anything, it was being too young to think of a better way to handle things. "What happened to the monster, Clark?"

"It came and tried to get you. I fought it off, then I woke you up."

Sam's eyes widened. "Well, are you okay? Are you hurt?"

"I'm okay. Its teeth and claws broke through my skin, but I just kept healing every time it scratched me."

"Is it . . ." Sam winced. "Is it dead?"

"No. I punched it until it ran away."

Sam nodded. He could work with this. "Well, what did it look like?"

"Like a person. He was a little shorter than my dad. He had green, glowing eyes, and claws and fangs, but other than that, it mostly just looked human." Clark frowned. "It didn't sound human, though. It was growling, like a wolf or something."

Strength, speed, claws, fangs, wolf-like growling, eating hearts . . . that sounded exactly like a werewolf to Sam. The time of the month was all wrong, and Sam had never heard of a werewolf being active during the day, or one with glowing green eyes. But the year before, when they'd encountered that Djinn, it was a little bit different from a regular Djinn because of the meteor rocks in Smallville. Green eyes might be a clue that they weren't dealing with regular werewolves, but with mutant werewolves.

The worst part about mutant monsters was that they were almost impossible to kill. They'd gotten lucky with the Djinn, but Sam didn't know if they'd have any such luck this time, especially if they didn't even know where it was.

"Did you see which way it went?" Sam asked.

"Yeah. I went to clean myself up by the creek, and I saw it going into an abandoned cabin."

Chills ran up Sam's spine. "See anyone else at the cabin?"

"Um . . ." Clark squinted. "I don't think so, but . . . it was a big cabin."

Dread pooled in the pit of Sam's stomach—there was almost definitely a whole pack of them there. "Think you could give me directions to the cabin?"

"I could, but why?"

Sam grimaced—Clark wasn't going to like this next part. "Clark, I have to tell Dean what you saw."

"What? No! Y-you promised!"

"I know, and I'm going to keep my promise. I'm going to tell the whole story without revealing your secret."

"How?"

"I have a lot of practice with this kind of thing."

Clark shifted his weight on the couch. "Are you sure?"

"You had to trust me a lot just to tell me your secret, right?"

"I guess."

"Can you trust me now?"

Clark's eyes grew shiny, and he blinked a few times. Then he looked up at Sam and nodded.