Board Thread:Warhammer 40k General Discussion/@comment-7671639-20130406191336/@comment-6078851-20130513024846

i would think basing the commander on the chapter would make more sense than the chapter on the commander - the commander has (presumably) spent centuries living the chapter's tenets and would be a mirror of the chapter's character.

although if you're creating a legion is your commander actually the primarch? if that's the case then basing the legion on him would be a the way to go.