The Avengers have undergone dramatic changes in membership over the years, with numerous heroes joining the team while others depart from it. As a result, each incarnation of Marvel's flagship superhero team tends to be very different from the one that came before it. Although things like the team's leader and the power of its members play an important role in the roster's overall effectiveness, the individual relationships with each other are easily the most important, and that was especially true in the 1990s, when two of the Marvel Cinematic Universe's newest Eternals heroes were on the team.

Almost every version of the Avengers is influenced by the chemistry between its members to some degree, but the early '90s incarnation of the team was practically defined by its members' distinct inability to get along with each other. Although events like the disbandment of the West Coast Avengers and the formation of Force Works are what most comic book fans think of when they remember this era of the Avengers, it was the romance between Sersi of the Eternals and Dane Whitman's Black Knight that truly defined it, serving as both the cause of most of the team's interpersonal drama and the catalyst behind the formation of the team's greatest adversaries.

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While Dane had been an off-and-on member of the team for decades, he rejoined the team with 1991's Avengers #329, by Larry Hama and Paul Ryan. Sersi was already on the team by that point, and it didn't take long for a mutual attraction to form between the new teammates. Bonding over their mutual willingness to employ more violent methods than most superheroes, Dane and Sersi's friendship quickly formed into a serious romantic relationship. After Captain America left the Avengers in disgust after they decided to kill the Kree Supreme Intelligence during the "Operation: Galactic Storm" crossover event, Dane became the leader of the team and his relationship with Sersi grew even closer.

However, it didn't take long for complications to arise in Dane and Sersi's relationship. Although Dane was in love with Sersi, he also felt an attraction to Crystal, princess of the Inhumans, who was also a member of the Avengers during this time. This created a love triangle between the three that caused quite a bit of tension within the team, which was made even worse by Crystal's complicated relationship with her estranged husband Quicksilver. To make matters worse, Sersi began suffering the madness-inducing symptoms of Mahd Wy'ry, a degenerative mental illness that affects long-lived Eternals. Rejecting the "traditional" method of curing the disease, in which the affected Eternal is killed and resurrected, Sersi instead formed a mental link with Dane known as a Gann Josin, relieving her of some of the Mahd Wy'ry's more severe symptoms and claiming him as her life-mate.

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While all of this was going on, the Avengers were also being menaced by the Gatherers, a group of Avengers from various alternative realities whose Earths had supposedly been destroyed by their native version of Sersi. Under the leadership of a mysterious villain known as Procter, the Gatherers sought to kill the Sersi of Earth 616 to prevent her from destroying it as well. After successfully framing Sersi for murder, Procter revealed himself to be the Dane of an alternate reality who had been driven mad after his own Sersi ended her relationship with him. Seeking revenge against every version of Sersi within the Multiverse, Procter traveled between realities and drove the Sersi of each reality he entered to insanity before killing them. Although the Avengers were ultimately able to kill Procter before he could kill Sersi, his actions caused her Mahd Wy'ry symptoms to worsen significantly, and she into self-imposed exile in another dimension with Dane at her side in 1994's Avengers #375, by Bob Harras and Steve Epting.

The romance between Dane and Sersi added a level of soap-opera-like drama to the Avengers that felt like something straight out of an X-Men storyline, complete with sci-fi shenanigans and psychic manipulation. Together with the already unusual line-up that the team had, the romance served as one of the many things that set this unusual incarnation of the Avengers apart from all of the ones that came before it, and one that continues to stand out as one of the most unique eras in the team's history.

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