'Eternals' fan-favorite pairing between 2 characters was only added to the movie after its stars improvised and the director saw 'sparks everywhere'

• Warning: There are spoilers ahead for "Eternals."
• The bulk of the film revolves around an on-and-off relationship between Ikaris and Sersi.

"Eternals" heavily focused on the 5,o00-year relationship between Sersi (Gemma Chan) and Ikaris (Richard Madden), but it's another budding romance that stole the film.

Despite a short amount of time on screen together, the chemistry between Makkari (Lauren Ridloff), a deaf superhero, and Druig (Barry Keoghan), an Eternal who has the ability to control minds, was a highlight of Marvel's latest superhero movie.

Fleeting moments between Makkari and Druig across centuries as they exchanged glances like smitten high schoolers felt more palpable than just about any moment shared between Sersi and Ikaris.

That wasn't lost on fans who felt a natural chemistry between Makkari and Druig despite sharing the screen for minutes.

Since the film's release, fans have suggested that Druig and Makkari's flirtation felt more convincing than that of Ikaris and Sersi.

They're not wrong.

Makkari and Druig didn't see each other for centuries and, like old pals, they fell right back into their natural rhythm as if no time passed in between near the film's end. Druig surprised Makkari by mentioning an artifact she finally managed to acquire, showing that no matter how much time had passed that he recalled how much that meant to her.

The two had googly eyes for each other in every scene they shared together so that's why it's surprising to learn Makkari and Druig's pairing wasn't in the original film's game plan.

Ridloff and Keoghan's real-life chemistry upon meeting inspired the director to lean into the Makkari and Druig pairing in the script.

During the movie's global press conference in October, which Insider attended, Ridloff said, through her interpreter, that a connection between the two "wasn't really something that was so apparent" in the scripts at first until director Chloé Zhao wanted them "to imply that there was a lot more to Druig and Makkari."

Zhao said she added the flirtation between the two characters because of "sparks" between the actors.

"I don't know if Lauren, you remember, it was your first time meeting Barry, the two of you started to just riff... You started to improvise," Zhao said. "And I go, 'Whoa, whoa, whoa. Wait, what's happening?' Sparks everywhere."

"Initially, that was not the intention," Zhao added for the relationship between the two characters. "I think really it was from you guys meeting that we saw that, and go, 'Maybe we should play into it.'"

Ridloff said she felt like it made sense for Makkari and Druig to come together because of some shared personality traits.

"I feel like that what actually brought them together is that... they're both very impatient, and they both have a lot of power," Ridloff said. "They're very powerful individuals and they're told to hold back, to hold themselves back. And I think that that, for Druig and Makkari, they're mischievous, and they also have fun."

It was a brilliant pairing.

Makkari and Druig's relationship felt more convincing and pure than the film's main love story.

Makkari and Druig's deep bond across centuries felt easy and natural. The Sersi and Ikaris pairing, on the other hand, came across a bit forced, so much so that the film needed to show a sex scene between the two to prove they loved one another.

Their relationship felt a bit toxic once it was revealed that Ikaris left Sersi (after being together for 5,000 years) because he couldn't be truthful with her about their duties as Eternals to let the Earth, eventually, be destroyed for the birth of a Celestial to occur. He tried to keep that secret from her until the Earth was gone.

When she and the other Eternals discovered the truth, instead of talking it out, Ikaris turned on his supposed family and decided he'd kill everyone, including Sersi, if it came down to it just so he could carry out a job. (So much for 5,000 years together.)

At the film's end, a series of flashbacks of the pair's relationship is shown to explain why Ikaris would align with Sersi to save Earth instead of kill her and stay loyal to his Eternal duties. You shouldn't need to replay scenes to remind viewers that they love each other at the very end of a two-hour plus movie, especially if the majority of the film was designed to convince viewers that what they had was real.

Yes, they loved each other, but their relationship didn't have a sturdy foundation of trust.

In contrast, you may have teared up a bit near the film's end when it initially appeared that Ikaris killed Druig, leading Makkari to cry out for the first time all movie in pain. She then raced off to beat Ikaris to a pulp to avenge Druig. The moment received one of the loudest cheers in theaters both times Insider screened the film despite the two having limited time together on screen.

Though Makkari and Druig never exchange an "I love you" in the film, their heartfelt reunion, with just their heads touching, told viewers everything they needed to know about how much these two care for one another.

It's a pure relationship that fans are hoping to see more of in the MCU.

Since Druig and Makkari make it through "Eternals" to meet Harry Styles' character, Starfox, in one of the film's two-end credits sequences, there's hope we'll see them again.

Though Ridloff told Insider she has "no idea what's to come" next for Makkari because "everything in the MCU and Marvel is always hush-hush," it seems likely there's more in store for the two in the MCU's future.