Berthe doesn’t do anything in particular, except show the faults of her parents. She’s an infant, then a small child in the novel, and she simply is not old enough to act. However, we learn a great deal about both Charles and Emma through their interactions with her. Emma’s love/hate relationship with the little girl plays up her own insecurities and fears, while Charles’s loving neglect of Berthe at the end of the novel reveals his inability to care for himself, much less for another living being. As the novel ends, we perhaps feel the worst for poor Berthe, consigned to a life of poverty in the workhouse, who did nothing to deserve her tragic fate.