TBAY: Minerva McGonagall Is Ever So Evil!

[jferer]

No: HPFGUIDX 39889

Mysteryreefer:"...if she [McGonagall] is indeed so powerful, why 
couldn't she conjure up a patronus to ward off the dementor from 
Barty Jr.?"

You have to practice stuff like the Patronus Charm, and she probably 
had no occasion to learn it, just like the world's greatest violinist 
can't play the guitar.  And why on earth would she be a plant for 
Voldemort?

Man, we really need OotP to come out....