Someone put something in here! I did. You're welcome. Now format the hell out of it.
It is known that the line between Craftworld Eldar and their dark kin is blurred. Although rare, it is not unheard of for individuals to cross this line, either way - for the pure to become corrupted, or for the corrupted to become pure. Such repentant souls can become valuable members of society, and they are given every chance to redeem themselves.
But what of the Chaos Space Marines? The Imperium is not so accepting a host as the Eldar. No Chapter or loyalist world would welcome any touched by the taint of Chaos, even if their heretical bonds had been broken. So what would these lone souls do? What would they become? Alone in the universe, with neither Emperor nor Chaos God to worship, such lonely Marines must make their own path.
And so is the story of the Metal Marines. A bizarre blend of Chaos Legion double-traitors, most notably Emperor's Children and Iron Hands, the Metal Marines (despite their myriad support groups and intervention schemes) are still stricken by their Warp-born afflictions. Ex-Astartes of the Iron Hands are filled with the need to build things, while their ex-Chaos brethren from the Emperor's Children are yet filled with a need for excess. However, thanks to the magic of
friendship science, their implants have been removed and the drugs have been purged from their systems respectively. The result is an engineer who is as much an artist as a mechanic; one who freed themselves from the convention and obsession of the Cult Mechanicus, yet still hate the chaos that threatens the Imperium from within and without. The result is a drastically toned-down version of a son of Fulgrim; many degrees more sane and much less obsessed with pleasure, they still feel the occasional urge, thankfully far weaker than the norm of their time as Chaos. The support groups advocate small doses of release to aid with their rehabilitation.
they ROCK. Ex-Emperor's Children fill the air with their bass and electric tones, striking non-lethal Blastmasters crafted by the iron hands of the Iron Hands. Ex-Berserkers call their fury of their Chaotic days to bear, turning raw anger into raging vocal tones. Combined, these band-brothers rock across the stars, performing in the halls or taverns of any who would have them. The Inquisition, certain that such totally excellent music is corrupting their youth into rock 'n roll rebels, hunts the Metal Marines to this very day, to no success.
It is rumoured that their impromptu Chapter Master seeks an ancient and powerful artifact, a guitar pick crafted from the chipped tooth of a Bloodthirster. It is said that such an artifact would generate music so totally excellent as to unite all the races in harmony, making the Gods of Chaos themselves totally chill the fuck out and stop eating everyone.
It is unknown what the Goff Rokkas have to say about all this.