“Hell is empty/And all the devils are here,” may not be the first Shakespeare quotation that most people think of, but the line from The Tempest certainly can be said to apply to Moriarty the Patriot. Not only is having William speak it a good indication of his education (whether it came from his stolen identity as a Moriarty or from his street child days in the abandoned library), it also espouses his philosophy of English society at the end of the 19th century. Hell must be empty indeed if the aristocracy is to be likened to devils, for they run rampant in a world he's bound and determined to change.
There's certainly a delicious irony to him speaking the line while his red eyes gleam out from beneath his black hood, which must make him look like a true devil to the men he's confronting, but it's also a nice nod to an element of Ripperology, the notorious “From Hell” letter. While there's some debate (as with all things Jack the Ripper) as to whether the letter is authentic or not, it has become inextricably associated with the murderer as part of the lore. And if, as Shakespeare said, Hell is in fact empty and the Earth overrun with its devils, then wouldn't that make the Earth Hell itself? So by that token, when the letter is sent “From Hell,” Moriarty the Patriot seems to imply that it is actually being sent from plain old London – new home of Hell's devils.
It's a great piece of detail from what is otherwise something of a rambling episode. It's not surprising that liberties are taken with the so-called canonical murders – Elizabeth Stride and Catherine Eddowes were killed the same day, but not found next to each other – though I do think that the description of second victim Annie Chapman being seen with a man in a deer-stalker hat prior to her death not being used in a story with Sherlock Holmes is a missed opportunity. But this isn't really about Jack the Ripper or his crimes. Instead it's a way to move Moriarty's plans ahead while introducing two distinct and important pieces of the overarching story: 1) the unrest between the denizens of Whitechapel and the police and 2) the character of Charles Augustus Milverton.
If you don't recognize that name, don't worry. He's another one of Holmes' villains, but he never really achieved the notoriety of Moriarty or Irene Adler. Like those two, Milverton only originally appeared in one story, 1904's “The Adventure of Charles Augustus Milverton,” and also like many of Arthur Conan Doyle's inspirations, was based on a real-life criminal, Charles Augustus Howell. Howell was a blackmailer and something of a smooth-talking conman; he's best known for having convinced Dante Gabriel Rosetti to exhume his wife to retrieve the poems he buried with her. Moriarty the Patriot's Milverton may well follow in that line, although Conan Doyle's is just a blackmailer who is eventually (read: at the end of the story) killed by one of his victims, with Holmes covering up the crime, which may be the piece's most notable feature. It's actually that which has the most interesting implications for his entry on the scene, because it's a case of Holmes acting somewhat like William, determining that because Milverton caused more deaths in his line of work, it's not worth pursuing the woman who killed him, who perhaps did the world a favor. That means that this particular character may be the one who forces Holmes to understand the Lord of Crime.
All of that is yet to be seen, however. This episode mostly just has William and Co. take out the men who are trying to use their fictional murderer, Jack the Ripper, as a means of accomplishing something marginally similar to what the Lord of Crime aims to do – but these men don't care about the collateral damage. Since William very much does, it's in his best interests to stop them, work towards ending the feud between the Yard and the people of Whitechapel, and leave Sherlock Holmes to pick up the pieces. It's a bit anticlimactic, honestly, although it does give us another good reason to remember that Louis may be the more dangerous brother (he is way more into killing than William) and the bonding between Bonde and Moran is kind of cute.
But good games require that we think several moves ahead. I think that in the long run, the things set up in this episode will prove to be important.
Moriarty the Patriot is currently streaming on Funimation.