Lets be careful of the terms and ideas we use to help explain addiction to nicotine.
Nicotine is a chemical compound. It is inorganic. It has neither soul nor mission, it harbors no agenda, it does not act with intent. It has no IQ.
Nicotine is NOT parasitic.
Parasites are organisms. They are living. They have an agenda or purpose, even if that purpose is as simple as self sustaining use of a host organism to ensure survival.
From Joel's original (with added emphasis):
......the idea that nicotine is somehow calling to a smoker who is off smoking for weeks or months is quite inaccurate. It is the person himself or herself whose own mind is creating the desire from triggers that he or she is experiencing. Those triggers are also not evil, they are just life events being experienced for the first time. I think the problems I have with the terms is they make nicotine seem to have more power than it actually does. The personification given to it can make an individual feel that nicotine has the potential of tricking him or her into smoking. An inanimate object such as a chemical has no such power. As John has said often nicotine has an IQ of zero. People do not overcome the grip of chemical addictions by being stronger than the drug but rather by being smarter than the drug.
Lets not give nicotine more credit than it is due. Lets not make it some cute and cuddly or evil and plotting entity--it is a chemical that alters brain chemistry. It is no different than heroin, cocaine or alcohol. These drugs don't have cute names given to them either and giving them to nicotine can start to make it seem different than these other substance--more trivial or less serious in a way. Nicotine is not more trivial than other drugs of addiction and in fact kills more people than all other drugs of addiction combined.