I love the fact that Du Cheng always tries to protect Shen Yi not only from physical dangers but above all from psychological ones. He knows the artist his smart, Shen Yi's mind is able to see things that no one sees, it is able to literally draws patterns and paths where there is no one. Shen Yi, through his art, is able to go down the human mind and it is both amazing and extremely dangerous because it can make him lose himself.
For this reason Du Cheng is constantly worried about him, for this reason he refuses to sign Shen Yi's authorization to review old cases, for this reason he gets really angry with him because Shen Yi, following his mind and his talent, ends always up to act recklessly, not thinking about his one safety. And Du Cheng is aware that he won't be able to protect him from everything. He tells him "I can't promise you to arrive always on time".
He can't bear the thought to arrive late, he can think to lose him both physically and mentally.
"I'll be out for a couple of days, keep an eye on Shen Yi" he asks his colleague Yan.
He is afraid to lose him.
But "When exactly did he start to care so much for the little artist?" he probably asks himself every time the image of Shen Yi crosses his mind and above all "Why does he care so much? Why is he so afraid that something can happen to him?".
The Captain knows in his heart the answers to those questions but maybe he does not know how to process them.
