Brigadier General Edison was a high-ranking member of the Central Command top brass, and as such, has been entrusted with Amestris' darkest secrets. Knowing full well of the Homunculi and their plans, Edison blindly follows King Bradley, who he seems to have a great deal of confidence in, as well as Father (whom he refers to as "The Good Gentleman"). (Source: Fullmetal Alchemist Wiki)