I had an odd thought this afternoon. Not being the "fluffy" type, I thought I would ask the experts. My apologies ahead of time if this is a common question, or is a source of nerd rage.
To start, the question is, "Could a Space Marine Chaplain also be a Techmarine?"
I was daydreaming today and envisioned something like the story of Joan of Arc, only "Joan" was a boy in this case. The kid finds some sort of Space Marine artifact out in the field. Because of his innate tech-savviness he recognizes almost immediately its importance, and takes on a pious pilgrimage to make sure the artifact gets back where it belongs (even though he realizes he'll almost certainly be killed on the spot for having dared touch the item). Instead of a grisly (immediate) death, however, he ends up impressing those he's relinquished the item to, both because of his bravery and also because of his single-minded piety, and so is inducted into the ranks of hopeful space marines. Throughout his training, the boy's dedication to humanity, to the Imperium, but most of all to the Emperor are never in doubt. At the same time, technology "sings" to him (as he puts it), and he instinctively knows how machines work, what ills they may be suffering from, and how to rouse their machine spirits. This is why and how he recognized the artifact he'd found for what it was and where it needed to go. In that light, he is seen as being as pious a devotee of the Omnissiah as he is the God Emperor.
Could this narrative play out in the Grim Dark?