Why a swan Patronus?

[Lisa C.]

No: HPFGUIDX 124106


Tammy Rizzo:
<snip>
> Swans are MEAN beasts! <snip> It didn't surprise me at all to
> find that Cho's Patronus was a swan.  Or, well, that SOMEONE'S
> Patronus was a swan, at least.  Oh, wait.  Were you asking why
> ANYONE had a swan Patronus, or why CHO had one?

I was wondering how a swan could be seen as anyone's protector. I 
had no idea that they were such mean creatures. I've only ever seen 
them as pretty birds.

Casil