Oh wow, thanks! I describe it jokingly as "Space Heroin" because I haven't named the drug yet, but it's something very similar in nature, just in a sci-fi setting with crazy space jerboas. I should probably actually draw him using sometime, while some might consider that crossing a line of good taste, a good portion of his story centers around his addictions and what actions he takes to feed them. I do know it's something injected (so I also have to design a futuristic space jerboa injection device), and a sort of blue-green color (I had at one point considered making it glow somehow, because science fiction, but I'm not sure I should go through with that although there could be valid reasons for a substance to glow beyond "science fiction lol"), and the effects it has on the user (being very similar to heroin), and even who he gets it from sometimes, and it's even the reason his eyes look the way they do (that's a nasty side effect of prolonged usage)... I just haven't assigned a proper name to it yet.

I do have to agree that not mentioning what a character is addicted to seems lazy, especially if it's actually important to the character's motives and actions and the character has any sort of development. When first introduced, or in a conceptualization stage I can see just describing them as a "drug addict"--but marijuana, LSD, and heroin all make their users behave in different ways so it's probably important to clarify that detail when it becomes relevant.