I just read the answers to a question related to talking patronuses (Was Shacklebolt's Patronus the only one that spoke?).
One thing I am always bothered by in relation to this is the question I am asking here. (I am not considering the more obvious things to do in similar situation, so let's ignore those for now; e.g. Send 1 of the kids (Harry or Hermione, Ron was injured) under the cloak/ Wait till morning and then send 1 of the kids/ Stun Pettigrew, etc.)
I will clear some assumptions that I am making here:
- Lupin knew how to make a talking patronus: Lupin was an order member with considerable knowledge about patronuses, if Kingsley and Arthur Weasley could do it, I am pretty certain Lupin knew how to do the talking patronus magic.
- Dumbledore could understand Lupin's patronus and knew enough about the Shrieking Shack: This is pretty clear from the books that Dumbledore knew the entrance to the Shack.
- The patronus does not keep blabbing until it gets to the desired person/location: So nobody else can figure it out except Dumbledore.
So why did they have to go strolling in the moonlight instead of just waiting for Dumbledore to arrive?