Snape's Attack on Flitwick

[houyhnhnm102]

No: HPFGUIDX 139522

Jen: 
[...]
> So McGonagall sent Flitwick for Snape, the only
> Order professor not aware of the battle. One 
> suggestion for Snape Stupefying Flitwick (see 
> more below ) is when Snape heard DE's were in 
> the castle, he knew he would have to assume his 
> DE-persona and didn't want Flitwick following 
> him and interfering if he appeared to be on the DE side.

houyhnhnm:

Besides the rumour about Flitwick's duelling experience in his youth,
there is also the fact that he was one of those patrolling outside the
maze during the Third Task of the Tri-Wizard Tournament. It suggests
that despite his small stature, Flitwick could be a formidable
opponent.  I think your explanation is the likely one.  As for Lupin's
remark, it is just Lupin reacting in a state of shock and dismay.