Join Date: Mar 2008
Location: Rochester, Medway, Kent.
Thats an interesting theory but I was thinking more along the lines of seeing what really happened during Sanguinius's last battle with Horus.
There has already been some speculation on other threads about what really happened when the Emperor faced Horus, how seeing Sanguinius dead didn't seem to bother him but seeing a custodes getting all toasty pushed him over the edge.
It's always been my guess that it wasn't Horus that killed Sanguinius, it was the Emperor.
Sanguinius and Horus were very close before the Heresy, what if, during their last confrontation, Horus manged to talk him round and turn him against the Emperor?
Horus is distracted by the Custodes and the Emperor kills Sanguinius, Horus is distraught at the loss of his closest brother and loses control, the Emperor uses this to finish him off as well.
If Mephiston has seen this as a result of falling to the black rage and has come out of the other side then that would put the future of the whole Chapter in jeopardy. Maybe he sees the need to fight for the preservation of humanity but knows that the Empire is built on lies. That the God Emperor is nothing more than a sham.