I love the voice you've created for Albus, the self-awareness (however reluctant at times), the possible necessary delusions, the insights. ("Brilliant" may be something he hates, but it's not un-apt). I also like the way you clearly characterize Gellert, too (or Albus's idea of him), through his apparent responses and the things he appears not to say. And I like the parallels of the opening and closing sections, humor changing to pathos.

Great lines:

Why dwell in the past, right? We only have so much future left in us
The essence of age

but I do find myself to be a somewhat formidable opponent, when I put my mind to it.
Ha! the essence of Albus, in a way. The "pawn" metaphor works well in this section, too.

And by the time you figure it out, the moment is gone.
Indeed