First some background:
My players recently investigated a spacehulk, fighting their way through some ghilliam, and ork ambushes. I sort of intended them to be deterred and retreat to their waiting thunderhawk, escaping the hulk as it began to crash into the planet's atmosphere, but they continued with their mission, and reached a still active warp core, to cripple and destroy the hulk. At this point, they saw through a huge rent in the hulk, the thunderhawks leaving, and the techpriest boosted their comm bead signals to get in contact with their thunderhawk, which informed them that the hulk was going to enter the atmosphere shortly.
They tried to find a solution, and came up with activating the geller field of the mars class cruiser which housed the power core. The techpriest burned fate to do this, and then activated the warp drive, successfully. They are currently drifting in the warp, trying to coax the machine spirit out of the warp. Meanwhile, one of the players, a psyker, who has a demon living inside his mind, used Time Fade, and slipped out of the ship (in a void suit) and was rescued when the local forces investigated its disappearence. So he is separated from the party. My question now is what should I do, and how? I was thinking of the following:
Option one is to travel in time to during the horus heresy or some other such event, basically just travel to an iconic event or time. I think that would be cool while it lasted but end on a "now what" sort of note. Next I was thinking of something with the Threnos zone, with it being corrupted or taken over by some rogue inquisitor or something, who perhaps presses them into service, or convinces him that he is on their side. Other ideas that I dont like as much are just being transported to a random area and lost for a while, perhaps the lathes, dealing with the gravitational fluxes, or, on a slightly better (I think) note, have a survival themed adventure on a feral or feudal world. Ideas? What do you think of the things I've put forth?