"It's not Malia," Stiles says. "If it's, it's, it's a coyote, there are thousands of coyotes in California. It's not the one who turns back into a teenage girl."

"Stiles," Stiles' father says.

"No, you're wrong!" Stiles snaps. "I know her, okay, she wouldn't do this. She couldn't."

"Stiles, I know you don't want to think—"

"I'm thinking, okay?" Stiles says. "I'm thinking there's no way Malia would do this. I'm thinking you're way off base, there's gotta be—It's too easy, okay, it's never this simple."

"Stiles, life isn't a Rube Goldberg machine," Stiles' father says. "It's Occam's razor."

"No, no, it's not!" Stiles says. "Occam's razor would rule out werecreatures completely, because they're ridiculous. Our lives are ridiculous. There's nothing simple about it."

"Stiles," Derek says.

"No, not you too," Stiles says sharply. "You can't—Malia's the one who found you, okay, she's the one who figured it out, look at this."

He pulls his phone out, taps rapidly at the screen.

"See? She's brilliant, she's Lydia-level, if she had killed something, don't you think she would've covered her tracks?"

Derek takes the phone from Stiles' trembling hand, looks at the screen.

The last text is just one word.

"'Nahual'?" Stiles' father says, leaning over Derek's shoulder.

"Yeah, it's, it's like a spirit animal, it's one of the oldest werewolf legends ever. The Aztecs—"

"Stiles—"

"She didn't do it, Dad," Stiles says desperately.

"Stiles, are you really trying to defend Malia on the basis that she would have killed a baby better?"

"No," Stiles says quickly, then, "Maybe? I don't—"

He drags his palm over his eyes. When he's done, he says in a small voice,

"What if I—" He pulls his knees up against his chest, secures them with his arm. "What if I… gave her something?"

"What are you talking about?"

"That night, the night we, you know—It was in Eichen House."

"Stiles, are you saying you had sex with Malia in an asylum?"

Stiles flushes. "It wasn't—planned—"

"No, I didn't think so," Stiles' father says. "I'm guessing you didn't use—anything?"

"I didn't really think to pack condoms in my overnight bag, no," Stiles says.

Stiles' father rubs his brow. "Stiles, you were possessed."

"Exactly," Stiles says. "What if I—What if we just think the nogitsune's gone, and really I just—passed it on? Like a—like a supernatural—"

"A supernatural STD," Stiles' father says tiredly. Stiles nods. "You think Malia is possessed by the nogitsune?"

"I don't know," Stiles says. "I just know it's my face on all those security cameras, I killed people, maybe—"

"Not every killer is possessed, Stiles."

"I was," Stiles says. "And we were together, and now—Isn't it just too much of a coincidence?"

"Okay," Stiles' father says. "Okay. What's the test?"

"What?"

"How can you tell if someone is possessed by a Japanese fox demon? What are the symptoms?"

Derek just watches Stiles, white noise blaring in his ears. He'd been possessed, he'd said that in Mexico. Casually, jokingly. Derek hadn't even really paid attention.

Hadn't realized what that meant.

Something took him over, something trapped him inside himself and used him to kill people.

Stiles' hands are trembling.

Derek thinks of the sick feeling of Paige's death reverberating all through his hands, how he could never—How it was always there, buried under his skin. How he would've given anything, done anything to claw the muscle memory out, the feeling of her going completely still.

It's still there, even now, her last tremors, the way she was suddenly heavier, the sound—

How much of that does Stiles have?

Derek sits down next to Stiles, doesn't say anything. There's nothing to say, nothing that helps.

Stiles and his father are still talking, their voices a vague hum in Derek's consciousness. Then they're hugging, Stiles suddenly small under his dad's arms.

"—rest," Stiles' dad says, when they pull away.

"What?" Derek says.

"I said, 'It's late. You boys should get some rest.'"

"Yeah," Stiles says, nodding. "Yeah, you too, Dad."

"We'll check that out in the morning," his father says. "I'll make breakfast, it'll be—"

"One to tell the grandchildren," Stiles says, but he waves his own sarcasm away. "No, it's—Yeah, we should just sleep. G'night, Dad."

Stiles' father heads to his room, but Stiles just sinks back into the couch, head in his hands, and Derek remembers: Kate.

Kate's back at the apartment, waiting, but Stiles is here, and Derek can't just leave him alone.

After the Malia thing, after—He'll tell Scott what Peter did, the pack will protect her. They're stronger, smarter, they'll be better.

And maybe it'll take Stiles' mind off things. Distract him.

Stiles is a small, dark eyed coil on the couch, hugging himself warm, shivering.

Derek lays his hand, careful, on Stiles' shoulder.

"Hey," he says.