Board Thread:Warhammer 40k General Discussion/@comment-69.143.134.163-20150419161351/@comment-26516936-20160106073001

It has been stated that the tragedies of the lost primarchs were "seperate" so it is highly unlikely that they occured at the same time. We also know that the 2 lost primarchs met their seperate fates before Corax was found & before Lorgars humbling & following corruption. Which means they likely happened in the time between the last decades of the 1st century of the crusade and the first decades of the 2nd.

The lost primarchs have been called "the Purged & the Forgotten" & in such a way as to hint that each is a seperate title. If that is true then "the Purged" would almost certainly have been destroyed by the Space Wolves as it's been mentioned many times that they had been used as the ultimate sanction at least once long before they attacked the Thousand Sons. In that case the "purged" primarch was almost certainly killed, probably for rebelling against the Emperor in some fashion.

The "Forgotten" though is a much more intriguing mystery as the term doesn't bring overtones of violence as does the first. It could mean rather than open rebellion the 2nd lost primarch was considered an embarresment for some reason, quite possibly by disagreeing so emphaticaly with the Emperor over something that he quit the crusade & refused to serve him. If that, or something similer, happens to be what actually happened then the ultimate fate of that primarch is very much in question. Was he executed? was he imprisoned in cryo? did he flee into the outer reaches & disappear? the possibilities are many & varied & leaves the option for a possible return in some form if GW decides to throw in game changing monkey wrench at some point. In fact i've theorised the possibility that this lost primarch is behind the rise of the Tau guiding them from the shadows into a society that meets his ideals (as multi species inclusiveness is a big part of those ideals it could explain what he & the Emperor disaggreed about enough to have him "forgotten" by all records).