Mfw I see this RP

https://m.youtube.com/watch?v=fvtQYsckLxk
For now, as a character I have two ideas. 

Either a Death Cultist vigilante creep, running from the law for killing a Hive Noble or something of the sort; he will offer his skills in exchange for being allowed free reign in the lower decks to do his weird interpretation of the Imperial cult. 

Alternatively, I was thinking of a Gatherer of the Grey Knights. An extremely old crusty warrior, having received a grievious injury some time ago. Unfit for combat he instead travels around the galaxy looking for psychic talents, and in the rogue trader as means to get around to far off edges of the galaxy for his job