Harper reminds me of a harpy, a "mythical, predatory monster having a woman's head and a bird's body." (
Webster's) It was a derogatory name for a woman once. Coincidently, in
Webster's the next word after "harpy" is "harridan." (= a shrewish woman)
I just can't picture someone playing a harp, much as I love the instrument.
Piper has pleasant associations in my head. Actress
Piper Laurie.