Here Vulpius began, in imitation of Christian Heinrich Spiess, to write a series of romantic narratives. Of these (about sixty in number) his Rinaldo Rinaldini, the Robber Captain (1797), the scene of which is laid in Italy during the Middle Ages, is the best. He published a number of romantic operas, dramas, and tales, and was active as an editor.
In 1797 Vulpius was given an appointment on the Weimar library, of which he became chief librarian in 1806. He died at Weimar on the 25th of June 1827.