system
Given the following post, respond as if you're commenting on Reddit:
human
[WH40K] What purpose/role did each Primarch have?

So i remember reading that each had a certain role in the eyes of the emperor, for example Leman Russ was his 'executioner' whilst Horus was 'warmaster' etc. I'm just wondering what each individual one was.
gpt
Horus was the only one with a "special" job, i.e. Warmaster, which is why he got a lot of resentment and jealously from the other Primarchs. He was seen as being favored and, in the eyes of some, for no good reason. Russ got a reputation as executioner because of his and his Legion's willingness to put the boot down on other Chapters in his name, not because it was his official job.