Honestly at the top of my head right now I could not tell you any fanfic ngl- but I'll give my two centimins as an harm reduction volunteer and person who has done drugs. (so dont expect any scientific mumbo jumbo lmao im just speaking as a person whos done drugs and has been around a lot of people who do drugs and has done extensive research on how to engage with substances in the safest way possible)
(WARNING: THERE IS NO COMPLETELY SAFE WAY TO ENGAGE W SUBSTANCES ALWAYS REMEMBER THAT)
First thing first, not all drugs are the same nor they interact the same way with eachother, obviously this also means that they interact different for each person but it's very unlikely that a stimulant (uppers) will act the same as a depressant (downers) or psychedelics. The withdrawals and comedowns are also incredibly different from each other.
We know Harry (and Jean) to be especially addicted to stimulants so I'm mainly going to talk about those (namely speed and stimulants most likely akin to adhd medication), though when people usually describe a drug use scene they are mostly portrayed in this mellow moment where they kind of just get stuck and droopy or dazed out (This is what a dissociative like ketamine would do).
In my experience, and also how electrochem describes it in game if we want to stay true to canon since that's the skill that tells us that Harry never really took "downers" that might not make his dick work (common ones in the partying scene with that specific sude effect include ketamine and oppiades), stimulants do the opposite.
Substances like speed, mdma etc etc are common "party" substances as they keep you up and jittery and induce an euphoric feeling. (this is very summerized)
These are substances with long recovery times rather than quick habituation because after the rush of seratonin they give, it takes the brain a really long time to be able to stabilize its seratonin levels again (for example you will find that the safest waiting time between MDMA consumption is six months to avoid habituation and long term withdrawal and damage). A comedown from this substances uselly looks like excessive tiredness, depression, brain fog, irratibility etc– from speed especially also a loss of apetite and the ability to produce saliva so all food kind of start to taste unappealing and has the texture of cardboard (this also happens if you keep redosing in a short span of time; at a 3 days long rave I kind of lost track of myself and spammed speed too much and it took me a good 2 weeks to fully regain a normal apetite and to find food appealing). The longer the substance has been used the longer it'll take for recovery.
My advice is look up harm reduction sites. Most of them are pretty extensive in the ways of consumption of different substances, the ways they interact with each other and what symptomps to expect in what timeline, and also harm reduction is a practice we should all be familiar with regardless of being drugs users or not (like we all should be carrying naloxone.)
I use PsychonautWiki Journal for when I go to multiple days long free parties and raves or when I am dealing with substances where I need easy access to check how much I took and when, it also tells me when I can expect for substances to be interacting with eachother if I take different ones in a short span of time and it has easy access to what combinations I should avoid and how high the risk is.
It has lengthy explanations for a plethora of substances on the ways of consumption, how the effects change based on dosage and way of consumption, what kind of substance it is and how it interacts with other ones.
Also here is a mixing chart from tripsit me, its a bit old so take it with a grain of salt.
WARNING! For educational purposes: I do not endorse any of these combinations. This chart will always be 'work in progress'. It is extremely important to be safe at all times!
From an emotional stand point, again as someone who does harm reduction I find it incredibly reductive when some authors engage with drug use with an "It was the drugs that ruined his life" approach, because it often is not the case.
Yes, we can all agree that drugs always absolutely come at a risk, especially of addiction‐ but addiction more often than not comes from when drugs are used as a copying mechanism for something that was there b e f o r e the drugs came into the equation. Something that is far more interesting (and also often actually helps understanding people with addictions or a destructive approach to drug use) is asking why do you have at this moment this relationship with this substance? What do you feel like this substance giving you? Was there something troubling before you engaged with this substance that now you feel it's resolved? Etc etc.
Anyways most of this is very summerized and im incredibly bad at explaining it, I really encourage people to do their own research cuz its a very cool and vast vast world
