But the others wouldn't let Professor Quirrell keep Harry to himself. It took almost ten minutes to get away from them all. At last, Hagrid managed to make himself heard over the babble.
"Must get on — lots ter buy. Come on, Harry."
Doris Crockford shook Harry's hand one last time, and Hagrid led them
through the bar and out into a small, walled courtyard, where there
was nothing but a trash can and a few weeds.
I think 'them' in this context only includes Hagrid and Harry because no others have been mentioned in later context, but I might be wrong. If this is the case, why didn't it put: "led him"(Harry) instead. Or is it idiomatic to include the leader himself in such contexts?
Best Answer
In this case, "them" does refer to both Hagrid and Harry. "Lead" does not necessarily exclude the leader, as it can refer to a general course of action:
For example, in the context of this story it would have been perfectly natural to have written:
(Edit) Note that it would have been fine to write
but the tone would have been significantly more mysterious, if not outright ominous. The collective "us" or "them" implies that, wherever they are going, they're going there together, but the singular "me" or "him" implies that, when they get to where they are going, Harry will have to face it alone.