I just recently picked up RT, and have been coming up with ideas for a campaign I was looking to run. I don't like to step on the toes of canon though, so I had a few questions. Without getting into it too much, I was thinking of having a 'Siren' type scenario. Decades ago a fleet surrounded a planet being swallowed by the Warp. All aboard were either killed or possessed. The sole survivor is an Astropath artificially kept alive, tortured and kept alive aboard the skeletons of one of the ships. Since the daemons can not possess him, they torment him causing his voice to shriek through the warp and draw in ships that are subsequently attacked.
So my main question is, what happens when an Astropath is cut off from their fleet? Being soul bound to the Emperor, would it prevent the daemons from holding the AP captive? Can the Emperor 'snuff out' corrupted Astropaths? Any help would be appreciated, thanks for reading.