When Kai Syaoran stood up, he felt an overwhelming urge to go and kill the Blue River gang boss. This emotion of complete and utter hatred for a human-made Kai Syaoran grip a nearby chair with all his might. The wood shattered like glass due to the great force.
These were the emotions of He Wen, the young man whose memories he had just experienced and in the process, he had even absorbed the human soul.
Kai Syaoran realized that there were drawbacks to this technique just like he had thought.
For over an hour, he stood in place without moving. He was sorting through the emotions ensuring that they did not affect his personality. Thankfully, the young man's soul had been too weak to affect Kai Syaoran's willpower that he had built up with blood and struggle.
He was finally able to regain control over his feelings but the fact that it had taken him an hour to to do so was very telling of how dangerous the Fiend Soul scripture was to the cultivator.