Tie Butian understood Chu Yang's intentions clearly. Even though he did not have any concrete proof, he believed that Chu Yang would not harm him or Iron Cloud Nation. Furthermore, he was sure that Chu Yang would not misappropriate the power given to him in some sort of evil scheme.
This was the reason why Tie Butian was willing to give it a shot. Because he was aware of Chu Yang's capabilities and sure that he would not harm Iron Cloud. At this point, he had actually desperately needed someone to help. He was exhausted from shouldering his burden as the ruler of Iron Cloud. He needed someone to share it with but none of the civil and military officials in the royal court were suitable to help.
This was because of their relationship between them, him being a prince and them being his subjects!
