For my first self made adventure, I decided that the mission is a small (yet significate) part of an almost mythic criminal mastermind. Who is only know through name, and reputation.
I named him; The Silent Man.
He's supose to be a heretek with the ability to see the future (through psyker abilities, or some sort of mathmatical formula), and communicate with his minions around his sector of the galaxy is a fraction of the time it usually takes.
I figure, the first few missions get the acolytes on the trail of this legandary criminal mastermind. Originally dealing in every crime under the sun that isn't considered straight out heretical, now he's gathering alien weapons and artifacts to take to who knows where, for who knows what reason. The common reason I see the inquisition and or the acoltyes believing is that it's for his own tamperings, or a private war.
I tend to go over the top when creating characters, sometimes going against the lore. Does this sound alright/plausable? I'd like to add more, but I was thinking of letting the PCs helping me to further develop him as they go. Or should I just start writing his back story now, and plan accordingly?