My theory.. Drawing from Impossible Astronaut, Day of the Doctor and Listen and recent rumours and pre-reviews.
Many of the pre-reviews for Heaven Sent do teasers..’Kenophobia’ ‘Pteronarcophobia’, ‘Archophobia’, ”Acrophobia’, ‘Aquaphobia’, ‘Electrophobia’, ‘Necrophobia’, ‘Amnesiphobia’, ‘Macrophobia’ was contained in one.
That suggests fear. The pre-publicity official photos show the Doctor in a castle, it shows creepy hands, dark rooms and the veil.
In ‘Listen’, the doctor uses this monologue.
‘Question. Why do we talk out loud when we know we’re alone?’
‘Conjecture. Because we know we’re not’
But, the theme was fear. We fear being alone and after the events of ‘Face the Raven’, he’s alone and facing a challenge.
Later in Listen, Clara returns to that Barn from ‘The Day of the Doctor’
A young boy is sleeping there. As Clara hides a man and woman enter.
‘Why does he have to sleep out here’
‘He doesn’t want the others to hear him crying’…
… ‘He can’t run away crying all the time if he wants to join the army.’
‘He doesn’t want to join the army, I keep telling you’
‘Well he’s not going to the Academy, Is he? That boy? He’ll never make a Time Lord.’
We assume Clara has stumbled on the Doctor’s parents. It’s never made explicit.
‘Listen’ as an episode deals in fear, from Danny/Rupert in the home to Orson to the Doctor with Clara linking them all.
One teaser this past week uses “The shepherd’s boy” as a one line teaser, other pre-reviews talk of The Doctor’s past.
I’m guessing that we’re going to get an insight in Heaven Sent into The Doctor’s past and a bit of pre-story.
We know from ‘Day of the Doctor’ that there are ‘Time Lords’, and it seems there are Gallifreyans.
Is the Academy where the Gallifreyan is made Time Lord. Is being a Time Lord more than just being from Gallifrey?
Another teaser said “We learn a new chilling fact about the Time Lords.”
River Song in ‘Impossible Astronaut’ –
“A Time Lord’s body is a miracle, even a dead one. there are whole empires out there who’d rip this world apart for even one cell. We can’t leave him here. Or anywhere.”
If gallifreyans are essentially Humanoid.. Then it’s technology of a sort that makes them Time Lord, like the way River Song was essentially a daughter of the TARDIS.
And.. The Doctor is a Hybrid. He’s an upgraded humanoid from Gallifrey.
Too far? We’ll see.