This is another reference to Byron. 'Mad, bad and dangerous to know' were the words Lady Caroline Lamb used to describe him after their first meeting in 1812. This assessment did not stop her embarking on a tempestuous affair with the poet, and even after Byron ended their relationship she continued to pursue him. If we think of Byron as Britain's first A - list celebrity then Lady Caroline can surely be called the first celebrity stalker.
A writer and poet herself, Lady Caroline's most notable work is Glenarvon, which is generally regarded as a thinly disguised portrayal of her relationship with Byron.
The words 'mad, bad and dangerous to know' have come to be associated, not only with Byron himself, but with the idea of a Byronic hero. Typically an outsider, the Byronic figure is often betrayed as a brooding presence, often prone to passionate, self-destructive behaviour. A classic example would be Heathcliff, the compelling lead character in Wuthering Heights.
Television trailer - Wuthering Heights.