Girls of the Forest by L.T. Meade

Penelope did not repeat her threat, but she watched Pauline. Miss Tredgold also watched Pauline. Verena felt uncomfortable, without quite knowing why. The keen vigor and joy of the first days at the seaside had departed. Pauline became pale once more, and Miss Tredgold's anxieties about her were revived. The Dales were a healthy race, but one or two of the Tredgolds had died of consumption. Miss Tredgold remembered a young -- very young -- sister of her own who had reached Pauline's age, and then quite suddenly had become melancholy, and then slightly unwell, and then more unwell, until the fell scourge had seized her as its prey. She had died when between sixteen and seventeen. Miss Tredgold seemed to see her sister's face in Pauline's. She did not for a single moment accuse the child of any wrong-doing. She did not imagine that what ailed her could have to do with the mind. Nevertheless she was anxious about her. Miss Tredgold had a good deal of penetration, but she was not accustomed to children. She thought that children of Pen's age were more little animals than anything else. It did not occur to her that a small child like Pen could have a mind of a very extraordinary order, and that the mind of this child could work in a direction which might hurt others. She did not suppose such a terrible child could exist.

Pauline was therefore more or less a prey to the naughtiness of Pen, who used her as a weapon for her own enjoyment. Pen was quite determined to enjoy herself at the seaside. She would have her bucket and spade and make castles in the sand as long as ever she liked, and she would play with other children, and would make acquaintance with them. She insisted also on going very often to the shops to buy caramels or chocolates. In short, she was determined that during her brief stay at Easterhaze she would have as good a time as possible. It is quite on the cards that she would not have had so good a time as she did but for the agency of Pauline. Pauline, however, in spite of herself, sided with Pen. She almost hated Pen, but she sided with her. She used to throw her voice into the scale of Pen's desires, and Pen in consequence got pretty much what she wanted.