Prince Zhao, ruling as Emperor He, was 10 years old at his accession in 88, so Dou took control as empress dowager and secured her authority by giving various positions to her four brothers, particularly Dou Xian. Because of his loyalty, Dou promoted Cai to (; "Regular Attendant"), where he served as a private counselor to He in political matters."After Emperor He took the throne, he became , and he participated in key strategic decisions.": "The emperor Ho Ti, on coming to the throne, knowing that Ts'ai Lun was a man full of talent and zeal, appointed him a privy counsellor.": "The Emperor Ho Ti, upon his accession, leaning of Ts'ai Lun's superior qualities and talents, named him private counsellor".</ref> This post gave Cai a high salary-rank of 2000 "shi", and was a limited position only eunuchs were eligible—and the highest they could hold, which also made him a chief eunuch of the palace. Cai gained the additional role of (; "Prefect of the Palace Workshop" or "Prefect of the Masters of Techniques") later in 88, or in 89."He was later given the additional post of Shangfangling."</ref> Also a eunuch-only position, Cai would have been responsible for the production of instruments and weapons for imperial use. The role had a salary-rank of 600 "shi"—though this was in addition to 2000 "shi" from his continued post.