Snape didn't make the Unbreakable Vow

[zgirnius]

No: HPFGUIDX 161662

Donna:
> If only the wand hand would cause the bus to stop, I'm certain only 
> the wand hand would count for something as important as the Vow.
> 
> "Wand hand" is referenced multiple times in HBP as well....
> 

zgirnius:
Harry's wand was in his hand, though. I assume that if he just stuck 
his hand out, even his right hand (wand hand, assuming Harry is a 
rightie, I can't recall whether this is established), nothing would 
happen either.

The thing with the Vow is, the person holding the wand and making the 
magic work is the Bonder, Bellatrix in our case. In other precedents, 
neither hand of Harry's put his name in the Goblet, and yet he was 
bound by the magic to compete in the Triwizard Tournament.

Of course, as others have pointed out, we do not know this level of 
detail of how the Vow works, so this *could* be right.

Addressing your other point about Snape being a leftie-are there any 
cases where language of this type is used to describe actual 
movements by Snape which suggest his handedness? I checked the 
Duelling scene (no joy) because it seemed a place where such a detail 
might come up in describing the two adversaries.

Because as you point out, 'sinister' derives from left, so if Rowling 
has indeed deliberately used all this 'sinister' language around 
Snape deliberately, it could be for the purpose of making him seem, 
well, sinister...