15 Iconic TV Relationships That Only Happened Because A Guest Star Had INTENSE Onscreen Chemistry With A Star

On a lot of TV shows, the biggest romance is between two main characters who date other people for several seasons before realizing they're meant to be. Sometimes, however, a short-term relationship a main character has with a guest star blossoms and takes both the audience and the showrunners by surprise with their chemistry — and they end up being endgame.

Here are 15 TV love interests who weren't supposed to last, but the chemistry was so good that the writers made them end up together:

Spoilers ahead!

1.On Arrow, Felicity Smoak was initially added to the show as a one-time guest star. However, Emily Bett Rickards' chemistry with Stephen Amell was so electrifying that, in Season 2, she was promoted to series regular and became Oliver Queen's endgame love interest.

Oliver had another love interest, Laurel, but the ultimate plan was for him to marry Felicity.

At a 2018 Heroes & Villains Fan Fest in Portland, Stephen said, "In our show, it was Oliver and Felicity, and it was going to be them no matter what."

2.On Veronica Mars, Logan Echolls was introduced as an antagonistic side character. However, Jason Dohring's chemistry with Kristen Bell was unexpectedly intense, and the longer he was on the show, the more fans rooted for him to end up with Veronica. It turned out that production was also "feeling it in the writers room," so they decided to steer the characters toward a slow-burn romantic arc.

Series creator Rob Thomas told Vox, "It was gratifying that the audience responded in the same way we were. It felt kind of undeniable to us. It allowed us to kind of slow-play that relationship a bit, because it wasn't supposed to happen. I think the first kiss might have been [Episode] 17 or 18? I'm a big fan of those proper British dramas where the romantic leads, like, touch each other's wrists, and it's like, 'Oh my god!'"

3.On The Big Bang Theory, Dr. Amy Farrah Fowler was written onto the show as Sheldon Cooper's "perfect match" from a dating website as a one-off joke in the Season 3 finale. It was Mayim Bialik's first foray back into acting since taking a long break to pursue neuroscience, so she wasn't sure if they'd bring her back. However, series creator Chuck Lorre was her "biggest early adopter and proponent," and Jim Parsons was also willing to fight to keep her on the show. Early in Season 4, she thought she was going to be written off, but they offered her a contract as a series regular instead.

In the book The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series, writer Steve Molaro said, "We, in the writers room, were into [Sheldon and Amy's blossoming relationship], but we didn't know where it was going to go. We didn't know they were to have a second date, or how that was going to play out and keep evolving through the years. But we went into it like we do with all additions to the show and all the characters: We're hopeful and trying to do our best to make it grow into something better and interesting; that was one of those that obviously did. But it took a little while to shake off the 'female Sheldon' description and let her become her own person."

Jim added, "At some point in Season 4 — I don't know if something caused it or not — I remember saying to Todd [Spiewak, his huband], 'I will not let this character go without a fight.' That was notable for me, only in that I almost never disagreed with the writers. But at some point I felt a certain way about working with Mayim that I was like, 'If for whatever reason we seemed to be weaning her off of this show as a character, I would go and talk to them.'"

4.On Buffy the Vampire Slayer, Spike "wasn't designed to be a romantic character, but then the audience reacted that way to it." After Buffy Summers' romantic storyline with Angel, showrunner Joss Whedon was against her dating another vampire, and he "backed [James Marsters] up against a wall one day, and he was just like, 'I don't care how popular you are, kid, you're dead. You hear me? Dead. Dead!'" However, against his intentions, Spike went on to have a redemption arc and become one of Buffy's main love interests.

On the podcast Inside of You with Michael Rosenbaum, James said, "[Joss] was angry at the situation. If it had been me in his shoes, I'd have killed me off immediately. ... He resented a situation where he had to deal with another romantic vampire, when his theme was that vampires are the problems you have to get over in high school. Evil is not cool. I respect that he's not interested in portraying that."

5.On Friends, Phoebe Buffay was originally supposed to end up with David. However, she married Mike instead because "Paul Rudd is so awesome that they sort of found a groove with him and [David] became more of just the grist for that mill...as opposed to the other way around."

Hank Azaria, who played David, told HuffPost, "It actually did sting a little bit. Whatever part of me is David the science guy who went to Minsk, which admittedly is probably a small part of me, but that part of me wanted to end up with Phoebe. So I was sort of sad when I didn't. ... [Paul] certainly has gone on to prove that he was comedically deserving of Phoebe's love."

6.On Glee, Blaine Anderson was not originally written as a love interest for Kurt Hummel, but he became "such a sensation in one week." Finding that there was "a hunger for him and a positive relationship role model," series creator Ryan Murphy signed a deal with Darren Criss to return as a regular. Then, he waited to see the audience's reaction to determine if Blaine should be Kurt's boyfriend or just his mentor. Of course, Klaine became the most popular pairing with Glee fans, and the two characters got married in the final season.

While he was still deciding what Blaine's role in Kurt's life should be, Ryan told AfterElton.com, "I didn't want to decide that until we got into sort of the middle of the season. We’re figuring it out now...Kurt will definitely get a boyfriend. The question is who will it be and how will it be."

7.Similarly, in the first season of Glee, Santana Lopez and Brittany Pierce were only side characters. However, fans excitedly embraced their relationship, and Naya Rivera and Heather Morris were promoted to series regulars. Santana and Brittany also got married in Season 6.

Naya told the New York Post, "I never thought this would happen, but I'm just so happy that it did. It's so shocking to me and very, very flattering that people love me because they love Santana. I feel so blessed."