I

"Chasing the dragon" is a slang phrase of Cantonese origin from Hong Kong referring to inhaling the vapor from heated morphine, heroin, oxycodone, opium, or ya ba (a pill containing caffeine and methamphetamine).
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Heroin.
Meth.
Zolpidem.
Adderall.
It didn't matter what it was as long as Ciel was able to get his hands on it and wish all the pain in his life away. This led the teen to be trapped by the web of addiction while Sebastian eventually became both his umbrella and the rain.