So I just recently found out the slaanesh wasn’t the god of excess originally but essentially the chaos god of sex in older additions. alot of her lore was focused around sex and sexual topics before GW rebranded her to be excess in all its form, which was a good thing. now I’m curious what was the lore around fulgrim’s fall during this time or was it not made back then before slaanesh got rebranded?
I think in the 2nd Edition and 3rd edition of the Chaos codices, there were only blurbs about the Emperor’s Children (And Fulgrim) pre-heresy. If any pre-heresy info at all. But it has been forever since I cracked either of those open and I have them in storage somewhere.
The first actual pre-heresy and heresy information I remember is from the Adeptus Astartes articles on White Dwarf ~25 years ago. I haven’t read those since they came out but I had a subscription then and I probably have those in storage as well. I looked it up and the issue with the Emperor’s Children is issue 255 but I didn’t find a PDF or a link for you. I think if you have a Warhammer subscription, you can look at any White Dwarf there.
Going off of (old) memories, I think the gist was generally Horus was extremely respected by Fulgrim and a great orator, so with a bit of mind altering drugs and some good ole manipulation, Fulgrim joined Horus.