Ah Yu's heart felt as if it had been struck by something, melting completely. He remembered that winter in college when Lin Wanqing shoved that crooked scarf into Zhong Hua's hands, saying, "It's a token of my affection." Zhong Hua immediately gave it to him, saying, "I'm strong, you wear it." The scarf was indeed ugly, the stitches so loose they let in the wind, but it was incredibly warm—he later learned that Zhong Hua had waited for him in the cold wind for forty minutes that day, clutching the scarf in his hands, his fingertips red with cold.

"So stupid," Ah Yu said softly, her eyes getting a little hot.

Zhong Hua smiled, reached out to ruffle his hair, but withdrew her hand halfway through. Instead, she picked up the warm water on the table and handed it to him: "Have some water, the hot cocoa is getting cold."

When Ah Yu took the water glass, her fingertips touched his hand. Zhong Hua's hand was cold, and there was a small scratch on his knuckles, as if he had been cut by something—probably when he was stuffing yarn in yesterday, and it had been scratched by the splinters of the wooden frame.

"I'll come to change the tampons in the window seams tomorrow," Ah Yu said, taking a sip of warm water. "I'm not afraid of heights."

Zhong Hua looked at him, her eyes shining like fallen stars: "Okay."

The afternoon sun gradually warmed, shining through the cracks in the window blocked by balls of yarn, casting a thin band of light on the floor. Ah Yu returned to his seat and continued adjusting colors; his fingertips were finally no longer so cold. He pulled up a photo of Qinghai Lake, the setting sun dyeing the lake surface golden red, and Zhong Hua's silhouette standing by the lake, holding his camera and adjusting settings.

He developed a fever after photographing the sunrise that day. In his delirium, he kept feeling someone wiping his forehead with a wet towel. Looking back now, it probably wasn't his imagination.

The wind blew through the window again, and this time it really wasn't cold at all. Ah Yu looked at the photos on the screen, suddenly picked up her camera, and pressed the shutter button, pointing it towards the window.

In the viewfinder, a gray-green ball of yarn is embedded in the wooden frame, like a button hidden in time. With a gentle twist, it can open up the warmth of the whole room.

He thought that once Zhong Hua's foot was healed, he would take him to buy new yarn—not to stuff the cracks in the window, but to knit something. He wanted to knit a scarf, with tight stitches so the wind wouldn't get in anymore.