Information about Rymer is sketchy. He was of Scottish descent, though born in Clerkenwell, London on 1 February 1814. In the London Directory for 1841 he is listed as a civil engineer, living at 42 Burton Street, and the British Museum catalogue mentions him in 1842 as editing the Queen's Magazine. Between 1842 to the 1867 he wrote up to 115 popular novels for the English bookseller and publisher, Edward Lloyd, including the best-sellers Ada the Betrayed, Varney the Vampyre and The String of Pearls. Rymer's novels appeared in England under his own name as well as anagrammatic pseudonyms such as Malcolm J. Errym and Malcolm J. Merry.