There's more to it than just his drug addiction. As you can clearly see by the lyrics "Wet and raving/ The needle keeps calling me back/ To bloody my hands forever", Nikki's heroin addiction is also the means by which Dr. X controls Nikki.
The way I see it is that X has conditioned Nikki's mind to simulate heroin withdrawls through the use of the Mindcrime codeword. This leaves Nikki very susceptible to suggestion. Furthermore, his heroin addiction is a safety: should he leave, he'll be cut off.
The literal of drug addiction controlling someone merges with the figurative level of one man utterly dominating another.
There's more to it than just his drug addiction. As you can clearly see by the lyrics "Wet and raving/ The needle keeps calling me back/ To bloody my hands forever", Nikki's heroin addiction is also the means by which Dr. X controls Nikki.
The way I see it is that X has conditioned Nikki's mind to simulate heroin withdrawls through the use of the Mindcrime codeword. This leaves Nikki very susceptible to suggestion. Furthermore, his heroin addiction is a safety: should he leave, he'll be cut off.
The literal of drug addiction controlling someone merges with the figurative level of one man utterly dominating another.