The worst enemies that Sherlock offers its titular main character are those that don’t seem to struggle to match our hero’s mental capabilities, or can turn his proclivities against him. This made Moriarty such an effective baddie – better than Sherlock with the media, more sociopathic, even snappier dresser – a lethal combination all told. Charles Augustus Magnussen – media magnate, friend of the Prime Minister, International Holder of All Secrets and this season’s end boss – is presented first and foremost as an amoral businessman, so terrifying because he carries himself in direct opposition to Moriarty. Where Moriarty is emotional, Magnussen is calm. Where Moriarty is screamingly insane, Magnussen is terrifyingly sane. What I’m trying to say is that Magnussen starts out dangerous, and just gets worse.
As the introduction of villains go Magnussen’s is more chilling than most, outing himself as both a power-hungry control freak and a sexual predator, made all the more horrifying by his completely blank expression. From his first scene with Sherlock and Watson, as he makes himself at home at 221b Baker Street, we see that not only that he’s morally bankrupt but also that Sherlock appears to hold him in a quiet respect, recognizing him as his match in most walks of life. Suffice to say, the lovey-dovey fun and games of last episode are well and truly over, apart from one hilarious scene in which Sherlock proposes marriage to his recent girlfriend Janine – Magnussen’s PA – to break into his office. This ends in disaster for everyone involved, of course, but it’s still a fun scene. Notably it all centres around “human error,” something Sherlock understands as the weak link in every chain, but also something that Sherlock falls prey to himself at the end of the episode, putting that chain of events in motion. In one fell swoop, that scene defines the trajectory of the episode and tears down everything that came before it in the series, everything that had caused the first two episodes to be practically written off by angry, entitled netizens. It also means that Sherlock adopted one of the techniques of the Mayfly Man in the last episode, entering into a relationship with someone’s personal staff to get access to them, blurring the line between hero and villain. In this world, no-one is truly good, nor truly bad, aside from Magnussen.
That scene is also important because it defines the future of Mary Watson. Sherlock discovering her in Magnussen’s office, threatening him with a gun, leads to the reveal that she is an excellent marksman with a secret past and that she will do anything, include killing both one of the most powerful men and one of the most gifted detectives in the UK, to protect her secret. But what is it? We don’t find out exactly, but revealing that she’s an ex-spy who stole her identity from another of the recently deceased – another Mayfly Man technique – suddenly makes her character more than a mere wife for Twitter to turn against. She’s a dangerous character in her own right, and in the process Watson gains two formidable protectors – a sociopath, and a psychopath. More on this later.