According to Dickens' friend John Forster's "The Life of Charles Dickens" (1872), Book I Chapter II, based on CD's own account, Fagin was in the main kind and protective towards Dickens, who described his using the name 'long afterwards' in Oliver Twist as "a liberty".

Hard to pin down the truth; but the most authentic authorities seem to agree that he was actually called Fagin and was mainly well-disposed. Why CD 'took the liberty' of using his name for a villain seems a bit mysterious.