WARNING: The following contains spoilers for Black Widow, now playing in theaters and available for streaming through Disney+ Premier Access.

The Marvel Cinematic Universe has been expanding, increasing its roster of heroes and villains as Phase 4 of the universe enters full-swing. And while Yelena (Florence Pugh) is an exciting new prospect for the MCU to focus on, and Taskmaster (Olga Kurylenko) presents a host of possibilities going forward, the real unexpected gem of Black Widow is the utterly ridiculous but surprisingly somber Alexei Shostakov (David Harbour) -- aka Red Guardian, who ends up with one of the most surprisingly affecting arcs in the film.

Red Guardian has been reinvented for the MCU, repositioned as a father figure to the young Natasha (Scarlett Johansson) and Yelena. Spending years together in America deep undercover, Alexei is revealed to be the Russian equivalent of Captain America -- having been given a variant of the Super Soldier Serum that gifted him with enhanced strength and endurance. He was even positioned to become a superhero like Captain America, with his Red Guardian persona teased to be a potential game-changer for the Soviet Union.

But in the end, he was instead locked away for the secrets he possessed, spending over a decade rotting away in a forgotten prison. It's only when his adopted daughters return to recruit him for their mission in bringing down the Red Room once and for all that he gets a taste of freedom again.

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Black Widow Red Guardian David Harbour feature

Alexei quickly establishes himself as a boisterous figure, fiercely loyal to the idea of Russia that he'd previously fought for. He aimed to turn his "family" into perfect soldiers for that dream -- seemingly failing to make the same connection with his adopted daughters that their "mother" Melina (Rachel Weisz) seemed to have. He even praises just how many kills they've gained over the years.

But as Black Widow progresses, the weight of everything he didn't get to experience isn't lost on him. Instead, Alexei finds himself asking questions about himself and the cause they fought for. And, in one particularly bittersweet sequence, Alexei gets sentimental with Yelena, recalling how her favorite song when they had been undercover was "American Pie" by Don McLean -- even singing it sadly by memory while trying to explain to her why he raised her as he did.

By the end of Black Widow, Alexei has thrown himself into the mission his family has taken on -- even effectively reclaiming the Red Guardian mantle and holding his own with Taskmaster long enough for the Black Widows to bring about the collapse of the Red Room and the release of the other women trapped in the clandestine spy program. He even makes his escape along with them, ensuring that Alexei can return for further adventures in the MCU.

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Hopefully he does, because Alexei is a surprisingly sweet inversion of one of the MCU's most persistent traits: poor fathers. The MCU is full of bad dads, with the most high-profile being Thanos and the physically abusive relationship he shared with his daughters. At their core, Thanos looked at Gamora and Nebula much the same way Alexei looked at Natasha and Yelena.

But through his reunited time with his family, it's clear that Alexei is reconsidering everything he ever believed in and fought for -- especially in light of what it did with his family. While he acts jovial and boisterous in the prison, and when he speaks of Russia's great history, he only seems to find peace when he opens up and allows his own emotions to really surface. Alexei -- on top of being consistently entertaining with his antics and imposing in a fight -- offers the MCU the chance to show how such an absent and cruel parent can realize their mistakes, and instead of being instantly forgiven or positioned forever as a villain, can actually have the ability and self-awareness to try and make up for their mistakes.

With Yelena (rightfully) poised to play a major role in the future of the MCU -- and the post-credits sequence even teasing her next target -- it would be fascinating to see how she deals with the continued presence of someone like Alexei in her life, and if someone like that could genuinely change for the better.

Directed by Cate Shortland, Black Widow stars Scarlett Johansson as Natasha Romanoff/Black Widow, Florence Pugh as Yelena Belova, David Harbour as Alexei Shostakov/Red Guardian, O-T Fagbenle as Mason and Rachel Weisz as Melina Vostokoff. The film is now in theaters and available on Disney+ Premier Access.

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