 Sophie Piper is known for her intimate friendship to Hedvig Elisabeth Charlotte of Holstein-Gottorp, the spouse of Charles XIII of Sweden.In May 1774, she accompanied her mother, who had been appointed by Gustav III of Sweden to welcome and escort the bride of his brother to Sweden.During the trip to Swedish Pomerania and back to Sweden, Sophie and Charlotte formed a very strong attachment with each other, and Charlotte was to be closely associated with the von Fersen family in Sweden.