Said was formally a member of ANBU, before joining Team 7. He used to live with his adoptive brother Shin, who had already died when his character was introduced. Sai did not seem to have any emotions whatsoever at first, but after joining the Team 7 he started to feel. He has deep connections to the ANBU, that exist even today. According to Danzo, Sai was one of the best at his job.
Orochimaru is one of the Legendary Sannin of Konohagakure. When the Second Ninja war ended, Orochimaru started working with Danzo Shimura. This was the time when the experiment leading to Yamato being created was done, and Orochimaru also worked on Danzo’s arm on which he planted multiple Sharingan. He has worked on several covert operations as well.