Warhammer 40,000: Space Marine fell foul of scheduling conflicts and THQ's bankruptcy before two further parts in the intended trilogy could be developed, meaning players never got to find out what befell Captain Titus. Now there's no need to use your imagination, as director Raphael van Lierop has discussed where he planned to take the story.
Speaking to Penny Arcade Report, van Lierop said "I had some big plans for Titus. The second part of his story was to focus on a 'Titus Unleashed' plot--basically there were forces arrayed against him that would see his loyalty to the Adeptus Astartes pushed to its limit, and his reaction would be to kind of 'go rogue,' and we'd see a different Titus, not quite as in control as we saw him in Space Marine. He would be kicked out as a consequence--exiled, which would basically be a death sentence for him."
van Lierop goes on to say that Titus would have come back filled with steely resolve to complete the trilogy in one final conflict, the other Space Marines coming to his side and helping him to eventually become the head of a new Space Marine Chapter.
Unfortunately, it looks like none of this will ever get to play out. But at least we know now, right?
Thanks, Shack News.