Huishe Yue lay flat on the ground feeling exhausted not because of the confrontation with Qilin Kai but the thought of training with Rui Fei. Rui Fei was his nephew and it was his responsibility as the uncle to nurture him but whatever Prince Rui did to him left the kid with so much aggression, aggression beyond the Huishe clan.
Don't look at the way he acts around Ji Yao and assume he is an obedient adorable cub. That was merely a personality reserved for his sweetheart. To everyone else, he was either cold, strict, unfeeling and sometimes rude. Ask this uncle and he will tell you.
He had just recently reunited with his estranged nephew but in that short span of time, he had come face to face with his true nature. If this cub was placed side by side with Huishe Yue's father they would be an exact replica of each other except that Rui Fei's level of aggression was beyond recompense.