What does 'turn on' mean here? He set the bottle back on the sideboard and sighed. It was then that his gaze fell upon Harry. “Oho,” he said, his large round eyes flying to Harry’s forehead and the lightning-shaped scar it bore. “Oho!” “This,” said Dumbledore, moving forward to make the introduction, “is Harry Potter. Harry, this is an old friend and colleague of mine, Horace Slughorn.” Slughorn turned on Dumbledore, his expression shrewd. “So that’s how you thought you’d persuade me, is it? Well, the answer’s no, Albus.”
Top answer
It means Slughorn changed his attitude, attacking Dumbledore in some way.
— Englishmaven
It means Slughorn changed his attitude, attacking Dumbledore in some way.
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