And a random question:

[drakyndra]

So, which bit do we think made the Doctor cry?

(Spoilers in the comments, obviously)

ETA: And just to compare, I asked fandom_wank for their answers to this question

Comments

[sparks-for-sale.livejournal.com]

All the mentions of Dumbledore and Grindelwald's misspent youth reminded him of his own and how the Master was still dead in "The Shakespeare Code".

Bonus old-skool proof: when Voldemort goes to find Grindelwald at Nurmengard, he's all decayed and skeletal, just like the Master was that one time. And then the Doctor gets in touch with his inner Snape and emos some more.