Jane Austen places the guardian/ward relationship at the centre of Mansfield Park, using it to interrogate the proper place of the child in the affective family. In its dramatisation of Fanny Price's attempt to be accepted and valued by the adoptive Bertram family, Mansfield Park provides sustained engagement with the legal idea of the ‘best interests’ of the child. The concepts Austen addresses transform, over the course of nineteenth century, into a legal recognition of the need to protect the child's emotional welfare – not just physical and economic welfare – within family structure. In the novel, the child's emotional needs are emphasised by recreating Fanny as an orphan and dramatising her mistreatment by her surrogate family. In the early nineteenth century, legal questions concerning the emotional care of the child are similarly raised by turning to the orphan and emphasising his or her uncertain family status and need for a legal guardian. Unable to rely on the clarity of biological bonds, the guardian/ward relationship forces the law to define the foundations of the family: is the best family for the child one that emphasises familial lineage, legal protocol, bodily maintenance, economic trusteeship, or emotional care? A turn to Seymour v. Euston (1803–6), a scandalous case that involves the Prince Regent (later King George IV), his illegal wife Maria Fitzherbert, and her claims to the custody of an orphaned girl, reveals the radical nature of arguing for the emotional care of the child.

In both law and literature, the orphan becomes an important testing ground for new definitions of the family. Just as in Mansfield Park, Seymour v. Euston positions the emotional well-being of a young orphaned girl as paramount. In the case, the Court of Chancery is charged with locating the correct guardian for the orphaned Mary Georgiana Emma Seymour (1798–1848), popularly known as Minney (or Minnie); it hears – and rejects – arguments that the emotional welfare of the child should determine the child's guardianship. Although Minney was cared for by Fitzherbert from infancy at the behest of her mother Lady Horatia Seymour, her guardianship is awarded to her uncles the Earl of Euston and Lord Henry Seymour. Minney's father's last will and testament names Euston and Seymour as guardians to his children; because Minney is born after the will is created, she is not named in it, creating an opening for her custody to be contested.