When he opened the door the sound that the Tardis makes when something is wrong (the sound of a banging gong under water) and he said something along the lines of “Of course, who else?”. So who do you think was in there?
Either 1. himself (Dream Lord, Valyard, or current incarnation), or, given the sound of the Cloister Bell, 2. the TARDIS dying.
I’m deadly curious on this one. D’you suppose we’ll end up finding out? Think it could possibly be Melody/River?
Now that you mention the sound it makes me think it could have been River trapped in the spaceman suit under Lake Silencio. I imagined he saw himself as a great warrior/conqueror. I think we’ll find out in the next episode when it all comes to a head but I suspect the thing The Doctor fears most is likely himself.
I hadn’t thought about it being the TARDIS. Wow that is quite possible. In the end, the Doctor figured out that the monster was preying on people’s faith, not fear. It makes sense to me that beyond anyone or anything, the Doctor has the most faith in TARDIS. Watching TARDIS die would be the thing that could break him. Fantastic insight! 
I think what is saw was himself dying alone. ( of course this means that the 1100 year old doctor that is killed on the beach by River Song in the space suit, is alternate Doctor made out of that flesh stuff…)
However, if River song could not go to Demon’s run, because she could not cross her own time line, how can she be on the beach and in the space suit to kill the doctor.
i don’t know what surprises this next episode hold… but i guess that’s why they call them surprises.
It’s not that she couldn’t cross the time lines. It’s that this had to happen so that we have River Song now. If she had interfered with it she would be the paradox. And we know they don’t last for long on Who.
As to the lake and her shooting herself. I think we know that was either a miss or a blank. She knew all along about where this was going. She had to play along so that it doesn’t get screwed up.
Oh well just a few more days and most, not all will explained. Can’t wait.
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