The DC Extended Universe launched with Man of Steel in 2013 and with each new film in the shared universe, the DCEU has continued to be dominated by a number of powerful relationships, be they romantic attachments or long-standing rivalries between DC's most popular heroes and villains.
These major relationships would influence DC characters and the decisions they made, and in some cases would potentially even threaten the DCEU in the dark possible future. However, the DCEU is also filled with examples of important albeit sometimes toxic relationships that may have influenced the characters more than the rest of the shared universe as a whole.
Harley Quinn & The Joker
One of the worst relationships in the DCEU was also a defining one for Margot Robbie's Harley Quinn, who first appeared in 2016's Suicide Squad before starring in 2020 Harley Quinn: Birds of Prey, and she is set to appear in James Gunn's The Suicide Squad in 2021.
While Harley Quinn's relationship with her breakfast sandwich has more positive aspects, there's no denying that Jared Leto's Joker and his twisted manipulation of his psychiatrist was important to the DCEU, though thankfully not very successful.
Enchantress & Rick Flagg
Suicide Squad also introduced Dr. June Moon/Enchantress (played by Cara Deviligne) first as a member of Task Force X, and then as their primary enemy when she temporarily took over Midway City with her brother Incubus.
Enchantress was initially held in check both by her captive heart and by Moon's romantic relationship with Task Force X leader Rick Flag (played by Joel Kinneman), though once she freed Incubus (played by Alain Chanoine) Flag risked her life to stop the threat of Enchantress, which thankfully paid off for Dr. Moon.
Flash & Cyborg
2016's Batman v. Superman: Dawn of Justice briefly introduced the entire membership of 2017's Justice League, though it wasn't until the team-up film that fans got to see the friendship start to form between Barry Allen/The Flash (played by Ezra Miller) and Victor Stone/Cyborg (played by Ray Fisher).
While they initially failed to relate to each other, they soon identified with each other as the "accidents" of the group. Their developing friendship was well-received by fans and led to rumors the two would star together in the upcoming solo The Flash movie.
Aquaman & Mera
When Aquaman (played by Jason Momoa) first met Mera (played by Amber Heard) in Justice League, they didn't have the friendliest beginnings following their battle with Steppenwolf for the Motherbox contained within Atlantis.
Their relationship stayed rocky until they were forced to go on a quest together in 2018's Aquaman and soon bonded, even sharing a kiss on the battlefield as they waged war against Ocean-Master. Their relationship may still in its early stages, but Aquaman and Mera are destined to make big waves as the rulers of Atlantis.
Batman & Wonder Woman
While it never developed into a romantic relationship, there was no denying the chemistry between Ben Affleck's Bruce Wayne/Batman and Gal Gadot's Diana Prince/Wonder Woman when they first met in Batman v. Superman was undeniable.
They impressed each other with a game of cat and mouse over Luthor's stolen data before building a foundation of trust that would ultimately lead to their formation of the Justice League following the invasion of Steppenwolf and the parademons.
Lex Luthor & Deathstroke
Fans only got a brief taste of the potential relationship that was formed in the post-credits scene of Justice League, which featured Lex Luthor (played by Jesse Eisenberg) and the DCEU debut of Slade Wilson/Deathstroke (played by Joe Manganiello).
The meeting between villains teased the eventual formation of an opposing team to the League like the Secret Society or the Legion of Doom, though plans for the DCEU have ultimately changed. Fans wanting more of Manganiello's Deathstroke will get a chance to see the character again in Zack Snyder's Justice League on HBO Max.
Wonder Woman & Steve Trevor
While Wonder Woman made her modern debut in Batman v. Superman alongside those titular stars, her origins would be told in 2017's Wonder Woman, which also introduced Chris Pine's Steve Trevor to the DCEU.
Trevor also brought the threat of World War I with him, which first inspired Diana to leave Themyscira and join the fight in order to help people, though she was traumatized by the ravages of war. Regardless, it was her relationship with Steve Trevor that first turned her into Wonder Woman, and continued to drive her mission long after his death.
Batman & Superman
The DCEU was built from the arrival of Superman (played by Henry Cavill) in Man of Steel which led to the destruction of Metropolis, which brought Batman out of retirement in order to investigate and take on the supposed new alien threat in Batman v. Superman.
While their relationship started off on a very bad foot and almost led to Batman crossing his ultimate line in battle with Superman, the two soon found common ground and a common enemy with Lex Luthor and Doomsday. This relationship was further explored when they led the Justice League alongside Wonder Woman against the invading forces of Apokolips.
Thomas & Martha Wayne/John & Martha Kent
It's impossible to talk about Batman and Superman without mentioning the people who raised them, as each couple's strong relationship had a large impact on the DCEU's greatest heroes, for better or for worse. Jonathan and Martha Kent (played by Kevin Costner and Diane Lane, respectively) raised their son with the compassion and sense of duty that would drive Superman.
However, it was the absence of the guiding hands of Thomas & Martha Wayne (played by Jeffrey Dean Morgan and Lauren Cohan, respectively) that shaped Bruce into Batman, and the relatable love for their parents that ultimately brought the World's Finest together in the end.
Superman & Lois Lane
The DCEU featured a darker take on Superman in Man of Steel that questioned his true purpose on Earth as well as his own humanity, though he started to see things differently when he first met Daily Planet reporter Lois Lane (played by Amy Adams).
Clark Kent's relationship with Lois Lane helped ground him among humanity which either treated him as a savior or feared him as an alien. Batman's "Knightmare" vision and warning from a future Flash in Batman v. Superman highlighted Clark Kent's need for Lois Lane in his life, making the success of their relationship important to the entire DCEU.