She finally realized her friend was one of those manipulators who had been taking advantage of her kindness.

manipulators 是名词 manipulator 的复数形式，由动词 manipulate（操纵、操控）加上后缀 -or（表示"做某事的人或物"）构成。manipulator 指"操纵他人的人"，通常带有贬义，指那些利用他人达到自己目的的人。