Both Sherlock and the MCU have obtained wide levels of success across diverse audiences, reaching millions of people all over the world. The two franchises share a lot in common in terms of characterization and themes, stemming from their mutual history of compelling text to back up film adaptations of hero and detective alike. 

Most people know that the MCU and Sherlock like to cast similar actors to portray their big-time protagonists. Benedict Cumberbatch has played both Doctor Strange in the MCU and Sherlock himself in the BBC televised series. Benedict Cumberbatch’s two prolific characters actually share quite a bit in common. For starters, Sherlock is able to see things that the average human can’t when he's looking at small details to solve crimes. Doctor Strange is much the same in this regard, because he can look into the fabric of time and see beyond what the human eye is capable of, including events that haven't happened yet, as established in Avengers: Infinity War. Additionally, Doctor Strange had quite the ego before crushing his hands, placing himself far above all other doctors working in modern medicine, similar to how Sherlock views himself to be better than any other detective or branch of law enforcement.

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BBC cast Martin Freeman as Watson alongside Cumberbatch, and the MCU chose Freeman to be Everett Ross in Black Panther, Civil War, and is going to make his return in Black Panther 2: Wakanda Forever. Beyond casting the iconic duo from Sherlock, Robert Downey Jr. also played Sherlock Holmes in the 2009 film Sherlock Holmes, just one year after playing Tony Stark for the first time. Robert Downey Jr. will become Sherlock once again later this year, as he retires his role of billionaire, playboy, and philanthropist to become a genius of a whole different breed. Jude Law, who plays Downey's Watson, also appeared in the MCU as Yon-Rogg in Captain Marvel.

Aside from the similarity in casting choices, the MCU and Sherlock have both mastered the art of creating complex protagonists. Looking specifically at the BBC televised series, Sherlock refers to himself as a “highly functioning sociopath” and frequently struggles to understand human emotion. Although Sherlock is one of the good guys, saving lives and hunting down the bad, his lack of empathy makes it hard to call him “a hero” because the title is too cut and dry.

Sherlock serves more as an antihero, similar to Deadpool, because he isn't necessarily bound by the same moral code everyone else is. Sherlock’s lack of empathy detaches him from the rest of humanity and makes it hard for fans to relate to him at all. It’s rare for a protagonist to be so distant from their viewers, but the BBC still manages to make it work. Despite his little regard for the emotions of others, the BBC humanizes Sherlock by giving him a strong bond with John Watson.

Marvel has done something similar in the past, during Captain America: The Winter Soldier. Bucky Barnes was still under the control of Hydra at the time, meaning he didn't really care for the well-being of anyone at all. Bucky was also detached from reality, just like Sherlock, because of the programming put in his head, making him another distant protagonist that fans couldn't help falling in love with. The MCU managed to bring Bucky back by using Steve to anchor him to his past pre-assassin self, mirroring the relationship between Sherlock and John.

Surprisingly, Bucky and John share quite a bit in common, having both been affected by the horrors they’ve seen during war. The BBC portrays John as a former war doctor struggling with PTSD that manifests itself as limp, as the traumatic result of helping wounded soldiers in battle. John goes to therapy in order to help him break down the mental blocks causing his stress, and he keeps a blog about his adventures in the present to aid him in letting go of the past.

Bucky also suffers from PTSD, and his metal arm used to serve as a reminder of his imprisonment before getting the original Hydra model removed. Like John, Bucky goes to therapy regularly and confronts the damage Hydra did to him after being injured in battle. Rather than keeping a blog, Bucky has a journal with a list of names so that he can find the people he was forced to hurt and make reparations to begin living his life in the 21st century.

The overarching themes present in both Sherlock and the MCU seem to be protection of the innocent, family (by birth or by choice), struggle to see oneself clearly, and delivering justice where it's due. Although widely different as a whole, both of these popular franchises use similar techniques to engage audiences and skyrocket their media high above other competitors. Whether or not the similarities between Sherlock and the MCU were intentional, the payoff has definitely proved itself to be worth it in the end.

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