Sherlock Holmes (born William Sherlock Scott Holmes) is the world's only consulting detective, a profession he created for himself. He is based in London and often consulted by Greg Lestrade of New Scotland Yard, usually taking his best friend and former flatmate, John Watson, on cases. He has a keen interest in unusual or bizarre crimes, without which he rapidly becomes bored, relying on nicotine to keep his brain active, although in the past he has dabbled in illegal drugs such as heroin for entertainment.