That scene in chapter 125-126 where Hua Cheng's reaction shows him reliving traumatic moments ay :(
In the darkness, the young soldier could see the flash of cold metal, and he cried, “Your Highness!” The sword struck, penetrating Xie Lian’s own stomach. (...) The young soldier was left in dumbfounded shock, and he fell to his knees next to his body.
“However…before that, there’s something I need to do,” he said softly. He raised the cold, jade-like, black sword. He stared at the sharp blade in his hand, a peculiar glint flashing in his eyes.
Wuming noticed that something was off. “Your Highness, what are you planning?!” But Wuming had no chance to stop him before Xie Lian turned the point of the blade on himself—and plunged the black sword into his own abdomen!
With that, he pulled Fangxin off his back. However, Hua Cheng resolutely pressed down on his hand. Taken aback, Xie Lian turned and saw Hua Cheng staring at him intently. Red was slowly spreading around the rim of his eye. “Gege, what are you planning to do with that sword?” he asked darkly.
XIE LIAN BLINKED. “I wasn’t planning on doing anything…”
“Then why did you draw that weapon?” Hua Cheng demanded.
“To…defend myself?” Xie Lian replied.
Hua Cheng’s expression was terrifyingly dark, and he squeezed Xie Lian’s hand harder. “How do you plan on defending yourself? Put that sword down!”
That was the first time Hua Cheng had ever spoken to him in such a tone or worn that kind of expression. It shocked Xie Lian.
When the flame gradually subsided and coalesced once again, the tiny ball of ghost fire was no more—in its place, the figure of a young man was gradually taking shape. The young man dropped to his knees in front of the scorched, black surface of the altar. Bent over deeply, he clutched his head in both hands. He bellowed in immense, devastating pain. He didn’t dare look at what had become of the person lying on the altar, for what lay there didn’t resemble a human anymore.
“Yes! I promised you,” Xie Lian replied. “Besides, there were so many weapons. Sabers, spears, swords—wouldn’t I have been reduced to mush if they all stabbed me? Ha ha ha ha…” He started to laugh, but the sound died in his throat. Hua Cheng’s head had jerked back to stare at him the moment he said the word “stabbed.” His gaze was hard to describe, but it obliterated all the words Xie Lian had to say. Without warning, Hua Cheng reached out and wrapped his arms around him, hard.
(...)
Xie Lian blinked and patted Hua Cheng’s back. “What’s wrong?”
“Your Highness, please don’t laugh like that anymore,” Hua Cheng whispered. He hugged Xie Lian tightly. “It’s not funny, really… It’s not funny at all.”
“…”