Everything that is known about them comes from a 3 paragraph blurb in the DA codex, I'm cool leaving it as the DA rules.<br/>They seem to that the 'warrior monk' aspect of the astartes to the extreme though, they love them some scripture pinned to the sides of their tanks and everyone gets robes. They also fight in the Halo Stars and Veiled Region. And ah.. they study the teachings of the Emperor a lot. Honestly I think half the appeal of them for me is the fact that their fluff is only the bare bones at this point, I like exploring stuff and building on fluff as I go along.