Ye Hongfeng seemed to have done a lot of things when she stabbed Gu Xijiu. She did not intend to kill Gu Xijiu or make her suffer, but wanted to steal her soul instead!
Apparently, there was someone else living in Gu Xijiu's body now, and it was most probably Ye Hongfeng! She must have used a venom which was not from the current era. The poison could change Gu Xijiu's physique so that other souls could control her body. The spell or poison must have forced Gu Xijiu's soul out of her body as well as it somehow got swapped!
If Ye Hongfeng's soul was in there, then where was Gu Xijiu's soul? Di Fuyi was very worried and quickly cast a spell to call her soul. However, he received nothing in return.
Based on Long Siye's personality, he probably kept Gu Xijiu with him instead of destroying her soul. Therefore, Gu Xijiu's soul was perhaps inside the cloned body!
Logically speaking, Gu Xijiu could no longer possess another body. The only way this was possible is if...