If you haven't read up through chapter 54
of Harry Potter and the Methods of Rationality
, go do that now.
Somewhere in the dimly-lit corridors of Azkaban...
From right to left: Polyjuiced Quirrel, casting Avada Kedavra; Auror Bahry, diving out of the way of Quirrel's death ray; Harry's Patronus, interposing itself in the way of the spell; Auror Bahry's duck Patronus, watching.
Edit: Apparently Bahry has a metal hand.