From theatrical_muse: When in your life did you feel the most alone?
If you really mean 'alone', then I suppose it was after my lifepod crashed on Chenga (not that I knew that's where I was). I had a broken arm, no one was answering my calls for help, and for all I knew, I was the only person on the planet. Mind you, I found there were worse things than that.
If you do mean 'lonely', then that whole year we were on Xenon Base was the worst in my life, I think. I felt useless, unwanted, and friendless (and I was right) and it hurt so much I used to drink myself into a stupor to stop the pain. The lowest point was probably after Avon tried to kill me over Malodar--yes, I was excess weight in more ways than one. Not long after that, we were all trapped in the base and I was helping Tarrant try to dig us out, and you know what? I really couldn't be bothered. I just wanted give up and get myself nicely drunk so I wouldn't be able to feel much when it happened. I knew no one would miss me and at that point, I wouldn't have either.