One of my more cracked-out (non-serious) predictions as far as things that had been referred to in earlier books and were relevant to the finale was that Lupin (and everyone else) telling him he had his mother's eyes was actually literal, and that this was why he needed the glasses, because seeing with his real eyes through the intervening, uh, film of the spare eyes was the problem. I couldn't resist including the notion, even though it's, you know, even more absurd than the death by snakebite.