Wei Wuxian, Lan Wangji, and Wen Ning left.
Jiang Cheng raced through the walkways of Lotus Pier as he had been instructed to by Wen Ning, and as he had to because he had to know. Anyone who wasn't smart or fast enough to get out of his way was ordered to pull Suibian from its sheath. To try and find any hope that what Wen Ning had shouted at him was a lie. Rather than everything else in these past years having been built on a lie.
After his golden core was crushed, Jiang Cheng thought he'd gone to Baoshan Sanren. He'd been ordered to claim to be Wei Wuxian, the son of her disciple. That she would heal his core. And it had seemed to work - he'd woken up on the side of that mountain with his abilities as a cultivator intact. However, it had all been a ruse. Wei Wuxian and Wen Qing had found a way to transfer golden cores. They had removed Wei Wuxian's own golden core to put in Jiang Cheng.
Jiang Cheng fell asleep that night still clutching Suibian, curled around it.