Just a quick question my friend asked me yesterday which has bugged the heck out of me. I wasn't able to answer very well and I too wish to know the answer now!
I know the Legio numbers (I through to XX) were given to the Astartes Legions in the order the Emperor created their genetic data...
What I don't know is in what order the Emperor found the Primarchs?
I believe Horus was first.
I'm pretty certain Alpharius/Omegon was the last (not know how/where the meeting went down, I'm assuming the Emperor knew about them being twins?)
Looking at it I can also speculate that Dorn, despite being on Terra, was found after Jonson and Sanguinius...?
This is making my face hurt from frowning.
Can anyone help clear this up?