When he assumed the title of count he married a Roman beauty Lorenza Feliciani, called Serafina. He travelled to all the major European cities, selling elixirs of youth and love powders and posing as an alchemist, soothsayer, medium, and miraculous healer.

But he fell foul of the Papal Inquisition, was sentenced to death and eventually died in prison.

Fosco, like Cagliostro is a charlatan with talent. No doubt Fosco has studied many arts. He is an intelligent self-educated man, with a hypnotic personality. Perhaps however his greatest trait is that of opportunism? His marriage to the 'spinster' aunt of Laura Fairlie has brought him some limited funds, and also her devotion. His membership of 'The Brotherhood' no doubt was also opportunistic and served a purpose at some earlier period of his life?

His mice, birds and, garish waistcoats other quirks may seem like innocent eccentricities but they are the very meat of street-theatre. So whilst attempting to belie Fosco's humble origin they only serve to draw attention to it.

We see Fosco's opportunism at its best, (or worst), at the point in Marian Halcombe's diary when she overhears Glyde telling him of the physical resemblance between Anne Catherick and Laura Fairlie. It is then that he conceives his plan which will cause his wife to inherit ten thousand pounds and Glyde twenty thousand.

But for all his cunning Fosco is neither completely evil, nor completely good. He does not shoot Hartright out-of-hand when pressed by him for a confession, even though he is already advanced in his plans to leave London. He also has identified himself with Marian Halcombe. He writes in her journal when she falls ill, and indeed it is his intervention that causes the London physician to be summoned and her life saved when the local doctor Dowson has failed to diagnose it.

It is these touches, deftly introduced by Collins, which make the Count credible as a character. He is a villain, and certainly a more talented one than Sir Percival Glyde but where Glyde is an 'aristocrat' seeking to preserve his heritage and consumed with guilt, Fosco is an opportunist attempting to make his fortune and enjoy the higher planes of life. For Glyde life is a kind of 'Rakes Progress', but for Fosco it is an opportunity for self-development and education which because of necessity, rather than malice, he sometimes calls upon the darker arts of deception.