The Good Little Girl by Thomas Anstey Guthrie

Her name was Priscilla Prodgers, and she was a very good little girl indeed. So good was she, in fact, that she could not help being aware of it herself, and that is a stage to which very many quite excellent persons never succeed in attaining. She was only just a child, it is true, but she had read a great many beautiful story-books, and so she knew what a powerful reforming influence a childish and innocent remark, or a youthful example, or a happy combination of both, can exert over grown-up people. And early in life -- she was but eleven at the date of this history -- early in life she had seen clearly that her mission was to reform her family and relatives generally.

This was a heavy task for one so young, particularly in Priscilla's case, for, besides a father, mother, brother, and sister, in whom she could not but discern many and serious failings, she possessed an aunt who was addicted to insincerity, two female cousins whose selfishness and unamiability were painful to witness, and a male cousin who talked slang and was so worldly that he habitually went about in yellow boots! Nevertheless Priscilla did not flinch, although, for some reason, her earnest and unremitting efforts had hitherto failed to produce any deep impression. At times she thought this was owing to the fact that she tried to reform all her family together, and that her best plan would be to take each one separately, and devote her whole energies to improving that person alone. But then she never could make up her mind which member of the family to begin with.