I hope that the third theory you just said isn't true that would be a dam shame.
"So, correct me if I'm wrong- but don't the Fallen kind of follow Cypher (the ones that didn't truly turn to Chaos anyway)? As Cypher makes his way to Terra, doesn't he cause riots and stuff like that?" Potemkis
I actually happen to have that old codex, which is about 144 pages and a true work of art, probably the best codex I've ever come across. Not only does it entail everything about the Horus Heresy itself and go play by play as to how it all folded out. But it includes all origins and reasons for all the main traitor chaos legions, so if you can find one, you will learn everything you need to know about the true makings of chaos.
But here is the section I thing you were referring to:
"Some whisper that Cypher may represent the Fallen Angels' only chance of redemption, and that his seemingly random appearances hide a pattern which reveals that he is slowly moving across the galaxy towards Earth and the Emperor himself. They also point to the fact that Cypher carries a sword which he never draws or uses in combat, and that this could be the fabled Lion Sword, wielded by Lion EL' Jonson himself, thought lost forever following the Primarch's final confrontation with the arch-heretic Luther. Whatever the truth of this, it is certainly the case that if he is ever in one place for any amount of time then his presence seems to attract others of The Fallen, though none know how they are able to find him or why they gather. Probably because of this, the members of the Dark Angels Inner Circle hate and fear Cypher more than any other Fallen Angel, and would willingly perform almost any act, no matter how vile, in order to capture and kill him. Cypher's continued existence bears testament to his almost supernatural prowess and ability to escape capture."