This story started with a rewatch of the charming Disney Robin Hood movie from 1973, the cartoon where Robin Hood and Maid Marian are foxes. The exaggeration of the cartoon gave me the idea to do a story on a supernatural Robin Hood.
9 Robin Hood movies later...
When you dig into the Robin Hood legend's origins, you discover how fictional it is. In the earliest extant texts, Robin Hood is just a dude who really likes the Virgin Mary and punching the cops. He has only a couple of friends, he's a commoner, there's no romance, and he doesn't have unbelievable skill as an archer. In fact, Robin Hood may have emerged as a generic term for bandit.
But as the Robin Hood stories got retold, new elements were added, much in the same way that modern superheroes like Batman and Superman have gathered and dropped elements over the decades.
The cheerful modern version of Robin Hood, the one we see in movies, actually owes a debt to Sir Walter Scott's novel Ivanhoe, where the bandit has a handful of scene-stealing cameos. This is the origin of the iconic 'splitting the arrow with another arrow'. The idea of the hero returning from the crusades, often used in the movies, is also taken from the character Ivanhoe.
As such, for centuries writers have tweaked the legend, with political implications - eventually the stories make him a lord, and send his adventures back in time a few hundred years to the reign of the widely disliked King John, on the theory that banditry is more excusable if the government is loathed and greedy. The idea of the character robbing from the rich and giving to the poor is in fact a fairly new addition to the mythos.
As a consequence most Robin Hood stories are wildly ahistorical - the forest laws against poaching weren't as stringent under King John, England didn't have friars yet so there's no Friar Tuck, there's no historical evidence for the Norman/Saxon conflict in this period because they had pretty much assimilated, etc.
Yet creators keep trying to inject realism into Robin Hood stories, with mostly silly results. The 1976 movie Robin and Marian, a grimdark version of the story where Richard the Lionheart is bloodthirsty and an aged Robin and Marian look back on their lives with regret, is the only film version I saw to depict the outlaw's proposed death, where he is poisoned by a nun and fires a last arrow into the air.
Most films don't include the death legend because it's pointless to kill Robin Hood. He's not real enough.
The other half of the story is Prince John. I decided to give him the best possible interpretation, as a cool-eyed reformer in a ruthless period following a policy of realpolitik, while his thug brother is off killing Muslims. So, no, Prince John did not really try to introduce the potato into England, or set up boys' camps. Alas, historical King John was in fact a bit of a dud, even if he wasn't as bad as Shakespeare's play would have you believe.
From there, I linked the Robin Hood character with the Green Man character that often adorns English pubs. Nobody knows how the Green Man started, so I took a big leap and linked it to the Druids. So that set up a conflict between Prince John as a man of the real world, trying to help, and a forest God who represents the seductive poison of medieval romance.
For the end, including Merlin is a huge indulgence, but when I knew that the trial would take the form of a magical ritual, it made sense to have an actual wizard with a strong tie to England's destiny.
For the ritual, I used a potlatch, a contest practiced by Indigenous peoples of Canada and North America, where power is demonstrated by destroying (or giving away) valuable items. The objects they forfeit are linked to the 4 minor arcana of the tarot - Wands, Cups, Swords, & Coins. The idea is that fundamental forces are being bartered to shape the destiny of England, with John even willing to sacrifice his own people (to the Black Death!) to impose a rational worldview over romantic ignorance.
Final note - of all the Robin Hood movies, I have a soft spot for the 1991 movie, with Patrick Bergin as Robin and Uma Thurman as Maid Marian. You haven't heard of it because it had the bad luck to come out the same year as the Kevin Costner movie. This one is fascinating because it aims for psychological realism, but tries to squeeze the absurd elements from stories into that worldview - this one has Marian disguised as a boy, it has an imposter Marian, a brief sequence where Robin disguises himself as an old lady, and the requisite swinging on drapes to rescue a damsel. It also has a very strong leftist bent. The miracle is that it almost succeeds in telling a Robin Hood story that almost could have happened, rather than a fantastic adventure.