What happen to the lost space marine lost legions?

Hey fellow Warhammer 40k fans! You know how much I love diving deep into the lore, and today, I wanted to chat about one of the biggest, most enduring mysteries in the Imperium: the two missing legions. It's mind-boggling to think that 20 legions were created, but only 18 remained by the time of the Horus Heresy. What happened to those other two, and their two primarchs? It's a question that’s kept me up at night! The official story is chillingly simple: they were completely forgotten from history. The Emperor himself ordered their names and their records erased. Even their own brothers refused to speak of them. This absolute silence is what makes it so intriguing. Was it something so abominable, so heretical, that even mentioning it could threaten the Imperium? One popular theory I've come across, echoing what some whispers suggest, is that they might have turned against the Emperor long before the Great Heresy. Perhaps they committed an unforgivable act, or their ideals clashed catastrophically with the Imperial Truth. Another grim possibility is that they became so corrupted by warp entities or Xenos influence that they had to be purged completely, perhaps to survive in some twisted form. Imagine legions so far gone that their very existence was a threat to humanity! Some theories lean towards a less destructive end, suggesting that their warriors were simply absorbed into another legion or disbanded, their identities stripped away. This could explain the genetic anomalies found in some existing legions, hinting at a hidden legacy. However, the severity of the erasure points to something far more dire than a simple reassignment. What truly captivates me is the idea that their history was rewritten, or perhaps, as the whispers go, it was never meant to be found. This deliberate act of monumental censorship by the Emperor himself indicates a secret so profound it needed to be buried forever. Was it a failed experiment? A discovery too dangerous for humanity? Or did these legions simply discover a truth that the Emperor couldn't allow to be known? The lack of concrete answers fuels endless speculation within the Warhammer community, and that's what makes this lore so compelling. It allows us, the fans, to fill in the gaps with our own grimdark imaginations. What are your favorite theories about the lost legions? Share them below – I'd love to hear your thoughts on this enduring enigma!