Robert Watson is an attorney in Croydon. He is the elder son of Mr. Watson, the clergyman at Stanton, and his late wife Mrs. Watson, making him the brother to Elizabeth, Penelope, Margaret, Samuel, and Emma. He married Jane, whose father he had clerked for, and they have a daughter: Augusta.
Six years ago, Robert's friend Mr. Purvis visited Stanton where he courted Elizabeth, but after Penelope set him against her, Purvis ended the courtship and soon afterwards married another woman.
At the beginning of the novel, Margaret visits the Robert Watsons for a month, hoping to make Tom Musgrave miss her, but when that doesn't work, Robert and Jane bring her back to Stanton (without telling Augusta where they're going) and stay for two or three days. Robert meets his sister Emma, whom he hasn't seen in fourteen years, but he spoils their reunion by speaking unkindly of their aunt Mrs. O'Brien. When they take their leave, Robert and Jane press Emma to come stay with them in Croydon, but she refuses.
According to Cassandra Austen, in Jane Austen: A Family Record, Robert would have become responsible for his sisters after his father died over the course of the novel.