When the singer Katy Perry spoke recently about her relationship with British comedian Russell Brand, not so long after their whirlwind courtship and immediately after their whirlwind divorce, she refrained from putting the boot in, despite Brand having ended the short marriage by text.
Her interviewer, from Elle magazine, suggested she might be attracted to the Byronic type: "mad, bad and dangerous to know". "Byronic?" Perry queried. "I'm going to remember that word. But that's not right. The men I have gone for are challenging, yes, but they're also wildly intelligent and poetic."
Byron himself, perhaps the original bad boy, was also rather poetic, of course. If his aristocratic mistress Caroline Lamb left that bit out of her timeless character assassination, it was probably because she felt it could be taken as read. Her dashing, unconventional lover was one of the most famous men in the world, and arguably the first international celebrity.
Today Brand is famous in much the same way, although even he might balk at a direct comparison with Byron. The British comedian and actor has fascinated his audiences and the wider public with a patented bad boy persona that seems a direct descendant of all those romantic, wayward heroes that followed in Byron's wake. His new relationship with the wealthy Jemima Khan, the campaigning daughter of the late British entrepreneur Sir James Goldsmith, only underlines his status as a modern Casanova, with a long list of ex-girlfriends behind him, including the supermodel Kate Moss.
But the truth about the real Casanova's exploits is still disputed, and it could be that the bad boy label owes more to literary history than it does to reality. It has become an appealing stereotype, although not always so comfortable for the women who are drawn in, or even perhaps for the seducer himself.
Born in 1788, George Gordon Byron was a lonely child. He appears to have searched for a place to belong, changing his surname in order to fit into various families. Literary historians record the sort of troubled relationship with an adored mother that might be seen to prefigure the restless love life that was to come. According to his fellow poet Samuel Taylor Coleridge, Byron's good looks were evident to men as well as women. His eyes were "open portals of the sun", he declared when they met.
One of Byron's great works chronicles the life of Don Juan, a man credited with similar erotic magnetism. The libertine's libertine, Don Juan is headed for perdition, yet Byron portrays him as an innocent with an unfortunate taste for recreating the "ambrosial sin" of first love: "Let us have wine and women, mirth and laughter,/Sermons and soda-water the day after." Classic bad boys are not villains, or lechers. Instead they are outsiders who attract women because they are such inappropriate mates.
The disturbing idea of a socially unacceptable monster getting hold of a prized damsel echoes down through legend, beyond Robin Hood and Maid Marian to Beauty and the Beast. But for feminist writer and literary theorist Marina Warner it provides a counterpoint to another fairytale archetype: the lucky good-for-nothing. "Many fairytales centre on a lazy boy, a kind of delinquent, before we get to the idea of the romantic hero," she says. "Like Aladdin, they were almost simpletons. 'Dumblings' is a German word for it and you find a lot of artless fellows like this in Grimms' tales. This was a kind of rascal, but more feckless than a bad boy."
In Western literature, Warner suggests, the difficulty has been finding a satisfactory leading man. "There is often a kind of deficiency because the princely hero is as dull as ditch water." Warner suspects that the early template for a bad boy was more likely the Italian sprezzatura, who was a dandy courtier with a certain fatal nonchalance. "Byron certainly would have known of this type, which comes from Baldassare Castiglione's The Book of the Courtier. These are refined and desirable men, but insouciant and careless too. There is also a sense that they are disdainful of other men."
And it is not an entirely harmless attraction, Warner feels, if it means that women justify being drawn to men who will hurt them. It has been a powerful tradition in fiction with cads abounding across the genres and down the ages, from the seducer Robert Lovelace in Samuel Richardson's Clarissa, to the Bronte sisters' lasting contributions: Mr Rochester from Jane Eyre and Heathcliff from Wuthering Heights. There has to be a sense of jeopardy in this kind of love, whether it is in Heathcliff's threat to Catherine Earnshaw's eternal soul ("may you not rest as long as I am living"); or in the blind devotion of Nancy to Dickens's thuggish Bill Sykes in Oliver Twist.
In The Picture of Dorian Gray, Oscar Wilde offers the bad boy a seductive line of argument: "The only way to get rid of a temptation is to yield to it. Resist it, and your soul grows sick with longing for the things it has forbidden to itself, with desire for what its monstrous laws have made monstrous and unlawful."
But modern psychology has attempted to explain the attraction more scientifically. "Women intuitively get attracted to brave acts of altruism more than to altruism per se," according to Daniel Kruger of the University of Michigan, principal author of a study on the appeal of cads. "A distinction between long-term and short-term relationships is important for understanding women's partner choices." The key, argues Kruger, is women want their emotions activated quickly and the "audacity" of a bad boy does the job at speed.
Whatever the psychological verities, writers have picked up the notion of the lady and the tramp and run with it. D.H. Lawrence gave us Lady Chatterley and Mellors; Margaret Mitchell gave us Scarlett O'Hara and Rhett Butler; Tennessee Williams gave us Blanche DuBois and Stanley Kowalski; and then Mad Men gave us a succession of women and Don Draper. Whether or not famous real-life sexual adventurers can claim that they were inspired by these potent fictional characters, they have certainly made the most of their reputations, even revelling in them. With the shining example of the reformed lothario Warren Beatty - married to Annette Bening for more than 20 years - perhaps at the back of her mind, Jemima Khan may be hoping to reform the errant Brand.
His ex-wife Perry has not been put off. She has had an on-again, off-again relationship with the John Mayer, a former lover of Jennifer Aniston and Taylor Swift. "Beautiful mind, tortured soul," she recently said of Mayer. "I do have to figure out why I am attracted to these broken birds."
The lure of the bad boy is still strong, it seems, in truth as well as in fiction. And truth, as Byron writes in Don Juan, "is always strange;/Stranger than fiction".
Robin of Loxley, the dashing outlaw of Sherwood Forest, in England's East Midlands, took on injustice as represented by the Sheriff of Nottingham and Bad King John, so legend has it. The thief won the heart of the fair Maid Marion despite his dispossessed and lawless status by virtue of his social conscience.
• Too much integrity
In Lord Byron's epic satirical poem, the legendary lover from Seville is cast as a hapless innocent targeted by a series of libidinous women. The unfinished work runs for more than 16,000 lines of verse and was judged to be hot stuff in its day.
• Lasted the course
A dark and wild force of nature, Emily Bronte's anti-hero is rough and rude, but scores highly for passionate loyalty. Although he marries another, there is never any doubt about his unhinged obsession with the haughty, headstrong Catherine Earnshaw, reaching as it does beyond death.
• Brooding intensity
As troubled as he is tall, dark and handsome, the lone wolf at the centre of the acclaimed HBO drama series Mad Men is drawn to all women, but has a penchant for those who are highly accomplished and beautifully poised. Initially regarded as a challenge, Draper is likely to bring misery to his victim.
• Suave, but lethal