Hao Da was two years ahead of him at the Institute when Yang Qing joined. They became friends through punishment. Hao Da had been a trouble maker too, though Hao Da's troubles were a bit different from Yang Qing's. While Yang Qing was always up to harmless mischief like faking an injury during cultivation so he could get a few days off, Hao Da's troubles were more of attitude.
He was from a well-respected rank 3 clan called the Hao clan that had deep roots in a rank 2 empire. However, his background made it hard for him to stand out in the Hao clan. His mother was a maidservant in the clan and became pregnant with Hao Da from one of the elders.
However, after his birth, both he and his mother were constantly harassed by the main wife of that elder. The elder acted nonchalant about the whole thing. Other than acquiescing to Hao Da getting the Hao family name, he never stepped in to defend them.