[HPforGrownups] Re:DH: The silver doe as Lily's patronus?

[Bart Lidofsky]

No: HPFGUIDX 172657

From: Debbie Grosskopf <Grosskopf5 at gmail.com>
>Isn't the Patronus supposed to be a unique creation for 
>everyone? How can Snape and Lily have had the same Patronus? 
>Isn't is supposed to be so unique that it is a secure form of 
>messenger?

Bart:
I've been trying to keep my posts to a minimum (and I'm waiting until after the flood to start looking at series-long discussions, such as Unforgivable Curses, Snape's personality, and Harry as a Horcrux) but here are a few things:

1) Where was it ever established that James' Patronus was a stag? 
2) I suspect that Lily's patronus WAS a doe, in that she was in love with an animagus stag. 
3) As I've stated before, the moment that I saw the doe Patronus, the very first thing I thought of was "Snape!" I was dead certain that was Snape's Patronus, yet as near as I can tell, there was nothing in the canon to explain this. Can anybody here think of where I might have gotten the idea?
4) Be that as it may, it is clear that Snape associated the doe with Lily. 

Bart