Even without considering he's not exactly the material for an Inquisitor-esque RP, he's wildly in conflict with the canon.
Space Marines don't "quit" to take contract work. It's neither allowed, nor would they want to (they're heavily religiously indoctrinated and committed before the implantation even begins).
Recruits with psychic potential are filtered out into the Librarium at an early stage and the likelihood of a non-Librarian developing powers is therefore almost infinitesimally low.
Also, nobody has a Space Marine for a father. The implantation process has to occur before sexual maturity, and even if it doesn't render them sterile, they're frakking monks. Seriously, getting sexually aroused while in power armour would be unpleasant.
If anyone has canonical counter-examples of Space Marine fathers, the author responsible should be found, abused with a cactus and a croquet mallet, then shot.
~~~~~
Sorry, but it seems you want to go in a direction very different to I was looking for in an RP. A Space Marine wouldn't work in the kind of setting I envision.
That said, it does seem we have several people who are interested in an RP. I've got an assortment of ideas - my Dark Heresy game has thrown up a few concepts, but they'd have to wait years at our rate of progress, by which point they'd have been forgotten or the plot will have gone the wrong way to still use them.
It'll take a while to develop them into a bit more than bullet points, but if we've got enough people interested, I can start putting something together.