1. don’t get too attached to any of the characters
2. not all weddings are happy occasions.
Sometimes the reason a wedding isn’t so happy is because people get dropped from the guest list during the event. The Red Wedding lost a few wedding guests in dramatic fashion. In the fan-dubbed Purple Wedding, only one character is dispatched. However, that one character was important - and not just because he was the groom. He was also the king. A nearly universally despised king, but a king nonetheless. King Joffrey meets his end at the hands of "the strangler" in Martin’s book A Storm of Swords. The strangler isn't a wedding quest with a criminally obvious nickname. No, the strangler is a poison made from a plant - plus sugar, spice, and everything not-so-nice - as described in Martin's book The Clash of Kings.
Do we have any poisonous plants here in the real world that could bring down a king? Oh yes – and more than one! There are a number of plants that produce chemicals that can be both medicinal and murderous. Three plants are routinely cast in fictional and non-fictional murder plots - belladonna (aka “Deadly Nightshade”), poison hemlock, and Strychnos nux-vomica (aka “strychnine tree”).
These three usual suspects all produce alkaloids that can be weapons in the wrong hands. Alkaloids share a loosely similar chemical structure – at least one nitrogen atom in a heterocyclic ring. Belladonna, poison hemlock, and Strychnos nux-vomica all make more than one alkaloid, but each has an alkaloid it's best know for. For belladonna, it's atropine and for poison hemlock, coniine. Strychnos nux-vomica's heavy-hitting alkaloid takes its name from the tree - strychnine.
Could any of our usual suspects be a real-world stand-in for the strangler? To determine that, the strangler's modus operandi must be examined. In Martin’s book The Clash of Kings, this poison is described as making "...the muscles of a man’s throat clench tighter than any fist, shutting off his windpipe." Taking some creative license with Martin's description, a real-world strangler stand-in must cause airway and/or neck muscles to clench (contract) and death by asphyxia. This requirement lets two of our usual suspects off the hook.
Both belladonna and poison hemlock can be stone cold killers, but their stand-out alkaloids tend to relax and paralyze muscles. Belladonna's atropine affects smooth muscle in a relaxation-to-paralysis way, including airway smooth muscle. Atropine, typically as a sulfate salt, has seen used as a bronchodilator - something that decreases airway resistance and increases airflow to the lungs. Atropine can certainly kill you, usually by messing with your heart, but it doesn't kill like the strangler does. Coniine also works to paralyze muscle, but it targets striated muscles - like skeletal muscle. This includes the ribs' intercostal muscles and the diaphragm, which are the respiration system's heavyweights.
What happens is that your body is slowly but surely paralysed while you're still fully conscious, starting at the feet and rising until eventually even the muscles surrounding the vital organs become affected. Death is caused when the diaphragm stops contracting and oxygen stops getting to the heart.
Coniine, like atropine, isn't a good fit for the strangler role. That leaves strychnine.
Like coniine, strychnine targets striated skeletal muscles - including those important respiration muscles. Unlike atropine and coniine, strychnine does not relax and paralyze muscles. Strychnine causes muscles to contract – violently and incredibly painfully. Within 10-20 minutes of ingesting a lethal dose of strychnine, the muscles of the face and neck convulse – fitting a bit with Martin’s description of the strangler. Convulsions spread to all skeletal muscles, coming in waves. The periods of contraction grow longer, with breathing impossible during a convulsion. Death by asphyxia results. That death could be quick – say a few minutes from the start of convulsions - or a person may suffer in agony for 2-3 hours (or more!).
Muscle contraction and death by asphyxia - strychnine and the strangler have a bit in common. Could strychnine play the strangler? Back to Martin's description of the strangler from The Clash of Kings…
It was made from a certain plant that grew only on the islands of the Jade Sea, half a world away. The leaves had to be aged, and soaked in a wash of limes and sugar water and certain rare spices from the Summer Isles. Afterward they could be discarded, but the potion must be thickened with ash and allowed to crystallize. The process was slow and difficult, necessaries costly and hard to acquire.
If we think of Joffery’s home as a sort of Europe, then the strychnine tree is definitely from half a world away being native to Southeast Asia. The most dangerous part of this tree isn’t its leaves, but the seeds of its fruit. The leaves^ contain strychnine, but not nearly as much as the seeds. It will take a lot of leaves, which seems like just the kind of hassle Martin is trying to convey in his recipe. Martin's recipe calls for the leaves to be dried (aged), followed by the extraction of strychnine with "a wash of limes".
What if Martin doesn’t mean lime, the fruit? What if Martin means lime (aka "quicklime"), a product of treating limestone? This type of lime is mainly calcium oxide and is alkaline. This lime has been used as part of multi-step processes to extract alkaloids from leaves – like the alkaloid cocaine from coca leaves or the alkaloid morphine from opium. The non-fruit lime is just one interpretation* of Martin's recipe, but it could be part of a "slow and difficult" extraction process. Sugar and spice is next, which is good considering that strychnine - like most alkaloids - has a bitter taste that will need to be disguised. Leaving nothing to chance, a beverage that will also help disguise strychnine's bitterness should be used. A beverage like red wine – which seems to be Martin's delivery beverage of choice and what King Joffrey is drinking at his end.
This strychnine concoction is nearly stage-ready, except… where’s the purple? The strangler is described as a purple poison. Is strychnine purple? No. In fact, many alkaloids - strychnine, cocaine, caffeine, morphine – are white crystalline solids. Here’s where Martin’s spices could help out again. Some spices pull double-duty as dyes. If dried berries are in Martin's spice cabinet, purple strychnine wouldn't be just a fantasy. Dyed strychnine isn't as weird as it sounds – some commercially available strychnine pellets for dispatching of rats, gophers, or other critters are dyed red or green.
In a pinch, purple strychnine could stand-in for the strangler. To be sure, we have to try Martin’s recipe with the lots of Strychnos nux-vomica leaves and spices for color to see if we could make our purple poison. Given how nasty strychnine is, we’ll need to strictly follow lab safety protocols. For even greater safety, never let Martin plan your wedding.
^In 2011, a suicide attempt via ingestion of Strychnos nux-vomica leaves was reported in literature.
*Another interpretation of Martin's recipe is that his lime is the fruit, working perhaps an acid extraction. The ash in Martin's recipe could be wood ash or soda ash, both of which are alkaline and could neutralize the acidic brew.
Image of King Joffery from Wired
Image of belladonna plant from NC State University
Image of poison hemlock from NC State University
Image of strychnine tree from Caroline's Botanical Art Blog
All chemical structure images are from chemspider