here's this again so instead of reblogging i'm just gonna do my micro-essay on a separate post, this post. Later is nigh.
Opioids dramatically slow the digestive system.
As we all know, Buddy is from the late Victorian era if he's from the Gilded Age, as Punko confirmed.
In Frankenstein (1818, Georgian Period), Victor Frankenstein begins to take laudanum following one of his many mental breaks within the novel to help him sleep. Laudanum is a tincture of opium and ethanol. The summary doesn't discuss his laudanum use.
In The Picture of Dorian Gray (1890, Victorian Era), Dorian Gray visits an opium den after killing Basil Hallward, to hide from his guilt of murdering his (apparent) lover. He is then encountered by James Vane, yada yada yada.
Obviously, the Gilded Age was between 1870 and 1890. And as we know, Buddy was born during that time, most likely at the beginning of the Age, making his last year as a human about 1889. When Oscar Wilde was finishing his novel, ish.
During this time, morphine and other opioids were used to treat essentially anything, especially since heroin just became synthesized in 1874. Migraines, grief, toothaches, neuralgia, back pain, sciatica, menstrual cramps, stomach cramps of any origin, dysentery, nausea, irritability, depression and melancholia, insomnia, et cetera were all treated by opioids, most notably morphine.
As we know, Buddy gets headaches and/or migraines. I'd imagine he has dental pain, considering he cannot take care of himself (being homeless), and he also probably still has his wisdom teeth which can cause some issues as well. Since he can't eat healthily, I'd imagine he also had frequent bellyaches and nausea, possibly even dysentery at some point. Buddy is also very, very easy to agitate. I personally like to think he has issues sleeping due to his time on the streets, as a sort of fear of being attacked in his sleep. Of course, opioids wouldn't help his insomnia, since he didn't want to sleep, but the point stands.
Morphine was also used to sedate patients as they had broken bones reset. Health insurance wasn't really a thing until 1911, and since Buddy was a street fighter (possibly to earn money, possibly as a way to keep himself safe with street credit) he may or may not have used this to his advantage.
Nox has no organs. None of the Keys do, as asked by Chase in Dreams By Day:
So, this implies the Keys don't defecate.
Obviously, Buddy eats quite a bit of, well. Junk.
Obviously, not eating healthy doesn't really help one's digestion. I speak from experience here. He was literally homeless; I don't think I have to expand a bunch on this detail.
Additionally, opioids dramatically slow and sometimes even halt the process of the muscles of the intestines contracting to move waste through (peristalsis). The colon absorbs more water, making The urge to defecate is heavily suppressed even when the bowel is full.
The body develops very little tolerance to constipation, and it worsens throughout the period of use.
During 1889, secondary treatments for constipation were very common, since morphine-caused constipation was well-known. Castor oil was a harsh laxative. Rhubarb preparations also worked, and since rhubarb is a root, Buddy might have picked some before, hopefully not after a frost.
Also calomel. Mercury chloride. This was also used to fight pretty much anything, including syphilis, bronchitis, cholera, ingrown toenails, teething, gout, tuberculosis, influenza, and cancer. By the late 1840s (pre-Buddy, but still applicable to his time period), it was being prescribed in heroic doses, due in part to the research of Benjamin Rush, who coined the term "heroic dose" to mean about 20 grains (1.3 g) taken four times daily. This stance was supported by Samuel Cartwright, who believed that large doses were "gentlest" on the body. As calomel rose in popularity, more research was done into how it worked.
The daily physical reality was chronic abdominal bloating and distension (belly visibly swollen and hard), persistent cramping and discomfort, a constant sense of fullness and pressure, appetite further suppressed by feeling, nausea from backed-up digestion, possible hemorrhoids developing and therefore worsening over time from straining, and general malaise.
The behavioral impact was significant preoccupation with bowel function (it nearly became background noise like "Hey doc I haven't shit in six months I think it's the morphine" "Oh well have you tried mercury!" "No but I will"), dietary adjustments/instinctively seeking food that may or may not help such as prunes, figs, other dried fruits and milk chocolate (hmm...) for the dependent rich, avoiding situations where access to a restroom would be limited, the humiliation of discussing problems with a physician (particularly acute for women, as morphine was generally prescribed to help soothe menstrual cramps and hysteria), and the situation was generally believed to be private even to discuss with doctors.
Opioid withdrawal does the exact opposite.