The Marvel Cinematic Universe is full of fascinating and emotive love stories, but the tale of Jemma Simmons and Leopold Fitz in Agents of SHIELD might just be the best of them. Initially introduced as Agents of SHIELD's resident British science geeks, the relationship between Fitz and Simmons has been a key part of the show since day one, but their love would blossom in a gradual fashion. What began as a deep and endearing friendship between two incredibly intelligent minds soon evolved into something more, as the duo's career path thrust them into life-threatening situations on a weekly basis.
Fitz fell first, declaring his feelings while the two scientists were trapped in a box heading towards the bottom of the ocean, and from there began a classic "will they, won't they" trope, as FitzSimmons' obvious romantic interest in each other was hampered by the usual relationship pitfalls of space-bending monoliths and secret organizations trying to take over the world. Fortunately, Jemma and Leo did eventually get together, marry and have a child, although in typical Agents of SHIELD style, said child was a fully grown man from the future. Nevertheless, the FitzSimmons story, told over the course of six seasons, has been arguably the best example of a romantic arc in the entire franchise.
What separates FitzSimmons from the other love stories in the MCU is that the couple has an entirely realistic relationship in a world full of superpowers and science fiction. Since they officially became an item, FitzSimmons' arc has avoided the soap opera-style route of constant instability but also avoided giving the characters their happily-ever-after. Instead, the husband and wife duo have remained faithfully dedicated to each other and strove to overcome the many obstacles that continue to block their path to happiness. This is something an audience can relate to, even if they can't relate to the obstacles themselves, and the FitzSimmons story therefore resonates far stronger the more common on and off-style relationships or the love stories involving superheroes.
Another major positive in FitzSimmons' on-screen relationship is how they are presented as genuine equals. Leo travels across the galaxy and breaks the laws of physics to rescue Jemma, she returns the favor by helping Fitz when he's been turned into a villainous HYDRA leader. Fitz heroically arrives to break Jemma out of Kree slavery, Jemma later fights alien criminals to save Fitz from a Chronicom Hunter.
All too often in film and TV, the standard boy-saves-girl trope is gender-flipped in a way that feels like an obvious attempt to demonstrate diversity, coming across as "the woman saved the man for once, look how progressive we are." Fitz and Simmons regularly stare in the face of danger and overcome overwhelming odds for the good of their other half, but never has one character permanently assumed the role of Knight in Shining Armor, and the other Damsel in Distress. Instead, the emphasis of their arc is how far both characters are willing to go to ensure the safety of the other and never does that dip into territory that feeds, or obviously tries to subvert, tired gender stereotypes.
Other relationships in the MCU start promisingly before falling out of focus, such as Hulk and Black Widow's brief tryst or Thor's romance with Jane Foster. Some happen simply because that's what male and female leads are supposed to do. But when considering the MCU's best love story, many might look to Captain America and Peggy Carter. Separated by Cap's time in the Arctic, the Avenger finally gets his dance in Avengers: Endgame. However, the audience only ever sees the bookends of their story. Their meeting and subsequent attraction is chronicled in Captain America: The First Avenger, their goodbye addressed in Captain America: Civil War's funeral scene, and then a happy ending arrives in Endgame. The real substance of the couple's time together is something Cap chooses not to share, largely because it's not the focal point of the films. Also, he kissed Peggy's great-niece.
On the other hand, Agents of SHIELD delves into the everyday of the FitzSimmons pairing, as well as the struggles they face and how their connection carries them through, and this makes it the premiere love story of the MCU.
Agents of SHIELD season 6 continues with "Inescapable" June 21st on ABC.