Treachery

Expanding the treachery of the "Air Walkers" (what the traitor TK are calling themselves atm)

Option 1 (Alex's option):
-upon the return from Ostium Ferdiad begins his rebellion
-TK are split more or less evenly, but traitor tribes are more contiguous and suffered less at Ostium so they have a slight advantage
-battle rages on Alessia for nearly a year
-Brennus finally takes a direct hand, meets Ferdiad in single combat and kills him, expecting this to bring the other traitors back
-they stay rebellious, and Brennus comes to the decision that it is his fault for upholding the planet's culture over the imperial way
-kills as many of the traitors as he can (some escape), blows up the planet
-he tells the wider Imperium that, yes, he had some traitors in his ranks, but they have all been exterminated, or as near to all so that it doesn't truly matter
                -charges his men with killing any traitors that happen to crop up over the years, declares them fomor and no longer human
-somebody other than the TK traitors has to back up the BA at Ostium, because as far as I know the loyal TK are still there fighting during at least the end of the heresy


Option 2 (my not as well thought out idea):
-keeps the way things go currently
-Brennus cannot keep the traitors on Alessia, they leave to try and head to Terra and most of the Legion heads out to stop them
-Brennus sends frantic astropathic messages for some time to any and every brother he can rely on, telling them that there are traitors amongst his forces and they are heading to Sol
-mostly he broods for a year, trying desperately to send communiques to anyone who will listen and wondering just how he screwed up
-concludes that he is at fault for allowing the divisions of tribes to remain when unity was needed, burns Alessia so he doesn't make the same mistake
-Brennus and the 1st Grand company set out to roam around the Galaxy trying to get to Terra, frantically slaying as many traitor marines as he possibly can to prove his loyalty
                -during this time the rest of the legion is fighting amongst themselves in Sol (how in the Nine Hells do we even GET there?)
-eventually Brennus gets to Terra, the BA and his traitor sons hold him up out in Sol until the VA get there
                -in this version, he kills Ferdiad sometime shortly before the VA show up, still in single combat


option 3 (really, this one is bare bones):
-Brennus actually tries to cover up the whole thing
-like option one, but Brennus never admits to the existence of traitors
-instead he claims that his world was assaulted by legions of Fomor and he suffered heavy casualties, he has to nuke the planet
-the TK put together some system like the DA have for hunting down traitors, but I don't know what yet
-this is probably my least favorite option, if only because the idea of a big over up just doesn't FIT Brennus, in my opinion