(So I came up with this a while back and wasn't sure if anyone else had brought it up. But I recently checked out The Mountains of Madness from the library, and remembered bringing this up with my friends a few years back and just felt like "preserving" it.)
This is going to sound crazy, but it's fun to think about, so hear me out: Have you heard of a story called The King in Yellow?
I got to looking at the source material and I'm stunned to think it may have been quite an influence on the plot of Pokemon Black and White. But I can't confirm anything since I haven't seen it mentioned as a reference anywhere in B&W.
More specifically The King in Yellow is a series of short stories where only the first four seem to be connected to the title. But there's some clear potential parallels with the first story The Repairer of Reputations, which is what I'll focus on.
So first off, the story's main character is a man named Hildred which likely has the same basis as Hilda and Hilbert would derive their names from.
Except plot wise he'd actually be more like N.
Hildred Castaigne is an unreliable narrator living in a “futuristic New York City” of 1920 who explains at the beginning that he used to be carefree and aimless but there was an accident where he got attacked and fell off his horse which gave him a blow to the head. After that he was taken into an asylum where he underwent a complete personality change, pouring over old documents and literature, basically a recluse, but he gained a strong sense of ambition as he never had before! (Sounds a bit familiar of another extreme recluse who came out somewhat brainwashed in his conviction, right?) This is potentially brought on after reading a play called The King in Yellow which the book we read gets its name from.
We don't get much info about the play itself except "references" to it about Carcosa, an otherworldly kingdom that fell into decay and mentions several places connected by lakes. (I'm not sure if they're all cities within the kingdom or neighboring kingdoms.) Supposedly the first act starts as a simple medieval drama but the second act is left very vague except that it "reveals irresistible truths" which drive the reader into madness.
With that out of the way, here's where things get... Interesting?
Out of the asylum, Hildred, at some point before the story takes place, has ended up in the snares of a "Mr. Wilde"; an "eccentric" deformed man with a mutilated arm and face (the story makes note of this at several points) who has an equally twisted delight in abusing his cat until she attacks him and we get the foreshadow that she’s going to kill him at this rate. (I'm sure some of Ghetsis' Pokemon would love the chance.)
Mr. Wilde may be crazy but he's said to be very smart. As the title "Repairer of Reputation" he gained wealth and power through blackmailing many powerful men (like the Sages?) and subtly raising an army of over ten thousand under a cult following by use of The King in Yellow and "The Yellow Sign" the king wears. Together, they plan to overthrow the U.S. government and begin The Imperial Dynasty of America under their new king Hildred! (Whether Wilde has an army or not is still debatable. Heck, even how much influence he has is debatable since we only have Hildred's word to go by. Obviously in Pokemon the answer is yes.)
Which is curious since I know a lot of people joked about with BW like... We're in New York. What's this whole deal with kings and the castle ruins? America never had a king.
Ah, but then the parallels come up again when Hildred is oh so ready to earn his crown but Wilde tells him there's a problem. His cousin, Louis, is also in line for the throne as they're both descendents from the ancient kingdom of Hyades. And while Hildred thinks himself to be the rightful heir of The Last King, Wilde tells him that he needs to do something about his cousin first and gives Hildred a long knife.
But Hildred, much like N, doesn't really want to fight Louis, and the two meet several times through the story over the course of several weeks (months?).
Now up to this point Louis had kinda been in Hilda / Hilbert’s position. At first he seems friendly with Hildred with Louis being concerned but not intervening with Hildred's ties to Wilde. But over time we see Hildred growing more irritated by Louis' sweet and sometimes boyish nature as he tries to humor him in his delusions even after learning about the whole kingship thing. (Much like we see N getting more aggressive as the story goes on because the player is so nice and good with their Pokemon, it's challenging what he's been told about what Trainers are like. Stop being wonderful, dang it!)
Eventually Hildred snaps. But instead of killing Louis, he confronts his cousin where he does finally reveal to him about being the King and shows him all the pages of The Imperial Dynasty records to reveal to him what's going on and demand instead that his cousin should abdicate his right to the throne and go into exile! Which Louis, having no interest in this, agrees. But Hildred also demands that Louis is forbidden from marrying then to end his bloodline. Even going so far as to say the conspiracy is going to kill the girl Louis is engaged to ensure there will be no one to challenge Hildred later on. Louis has finally had enough of this! When Hildred flees, his cousin goes after him.
(There's not really an equivalent to the murder thing, although unlike the book, it'd be about this point that the takeover occurs and Plasma has threatened to crush Alder. But that's more between him and Ghetsis. Either way, we save Alder and Hilda / Hildred is in hot pursuit of N into the Plasma castle!)
Hildred then ends up running back to Wilde's place and takes his crown and cloak in victory as he thinks he'll finally be king! ...Except Wilde ends up dying on him (finally pushed the cat too far and she murdered him.) Hildred realizes that without Wilde and his conspiracy, he personally doesn't have the means to take over. He has no connection to this “army”, he cannot read the ledger of "powerful men" to manipulate. Without Wilde, he is NOTHING. This fact suddenly has him spiralling into a full on mental breakdown before the police show up with Louis and end up taking Hildred away and we learn later he ended up back in the asylum. (Which is kind of what happens with Ghetsis in the end, he lost the one person holding his plot together, goes into a fit of madness, and albeit much later is one of the few Evil Leaders to actually get arrested.)
So BW doesn't really follow the plot but the point is, I think there’s actually several elements that could be derived from this specific story. The young man being brainwashed and convinced he’s going to become king of a perfect society that was lost ages ago; led on by an even more deranged man who appears to have been mangled by the creatures he tortures with delight and who has been making all of the preparations for a full scale government takeover by amassing an army in the shadows. There’s a fight for the throne when it turns out the prophecy speaks of two heirs that need to fight each other, note the second “heir” is completely oblivious to this and just gets dragged into the lunacy more and more as they try to foil the plans of this takeover. And while it doesn’t induce madness automatically, Plasma believes that in order to get people to fall in line, the king merely needs to show the public that they’ve obtained the Sacred Dragon which gives them authority, while in this case it’s said that all those who see The Yellow Sign have no choice but to bow down to them.
It’s just… I’m probably grasping at straws, but the parallels I see just have me fascinated.
At least in the end of BW, Ghetsis is the one to have the full out melt down upon realizing without his key to controlling the masses he's nothing instead of N like Hildred did. Not to say N doesn’t have his own lingering issues from all this, but unfortunately Hildred ended up dying in the asylum where I’m sure Louis wished (after offering several times) he could have helped him. At least Hilbert / Hilda may stand a chance.