Okay but I just thought of something. In Harry’s first year, his Nimbus 2000 started bucking him off and basically trying to end him. Now we know it was Quirrell but to the average eye it probably just looked like the broom was defective. McGonagall got him that broom. And she was watching the game.

Imagine how horrified and guilty she must have felt to think that the broom she’d bought for this young boy might be trying to kill him.