I've come across Elia's Peattie, The Shape of Fear but I can't figure out the meaning of the following sentence. Is it an idiom or phrase?
"Purity seemed to dog his heels, no matter how violently he attempted to escape from her. "
Some dogs (sheep herders) nip at the heels of the sheep, to direct them.
So the implication is not merely of following, but of changing the behavior of the one followed.
Yeah it does not mean just to follow, but to follow so closely as to be a nuisance, since the one doing the dogging is following you so closely and constantly and as if to bite you on the heels that you want to kick the SOB.