Typical bad boy behaviour, fictional and in real life:
1. Relentless promiscuity, until he meets our heroine, falls deeply in love and changes his ways, becoming forever monogamous. Hmm. Remember that proverb concerning leopards and spots? Much more likely you'll turn out to be just one of the crowd.
2. Dangerous driving, particularly of large motorbikes. Don't get too fond of him; doctors refer to motorcyclists as organ donors.
3. Drug use and/or excessive drinking, possibly smoking. This will spoil his gorgeous looks and his health, given time.
4. An explosive temper with a tendency to beat up people he is in conflict with. You'll be visiting him in prison if he makes a habit of physical assault. Plus, cauliflower ears and chipped teeth are not attractive.
I'm yawning already...