That's because a large part of the conversation was missing, my dear Andromeda.
Beautiful, really, especially the Andromeda/Tonks underlying tones. And Alice is just absolutely wonderful.
Making Sirius the look-out instead of Peter was wonderful as well, way to break the mold.
One question:
1. Is Snape in Androemda's year? If not, why is he in her potions' class?