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.

  The CW / Via

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.

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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.

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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.

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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 opposed to the other way around."

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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.

  Fox / Via Hulu
Fox / Via Hulu

While he was still deciding what Blaine's role in Kurt's life should be, Ryan told, "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.

  Fox / Via Hulu
Fox / Via Hulu

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."

8.On Full House, Lori Loughlin was reportedly brought on as Rebecca Donaldson for six episodes, but her chemistry with John Stamos, as well as her popularity with the audience, helped make her into part of the main cast and Uncle Jesse's eventual wife.

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John told People, "Well, we had — not just us, everyone on the show had — this undeniable chemistry. People loved seeing us together."

9.On Once Upon a Time, Colin O'Donoghue decided to play Captain Hook as a "charming bad boy" from the beginning. The showrunners were such "great admirers of Colin’s talent and of the way he portrays Hook" that he was promoted to series regular and made into Emma Swan's main love interest before his first episode aired.

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In a statement to Entertainment Weekly, showrunners Edward Kitsis and Adam Horowitz said, "We've much more story to tell with his character that we're excited to share with the audience."

Colin told TVLine, "I had a very specific idea as to how I would play him, and [the showrunners] were on the same page from the get-go. I just made an innuendo about anything that I could — that was part and parcel of what he was — but I knew I could do it in a cheeky way so that you could kind of get away with it."

10.On Supernatural, Misha Collins was cast to play Castiel for three episodes, but fans loved the character so much that he was brought back in longer stints and eventually stayed on the show for 15 years. Fans were especially passionate about Castiel and Dean Winchester as a romantic pairing, and in the final season, Castiel finally declared his love for Dean — right before he died.

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Viewers accused the show of queerbaiting for years, then, after Castiel's death, they accused them of perpetuating the "bury your gays" trope.

Misha told Entertainment Weekly, "There are just a ton of die-hard Supernatural fans that are a force to be reckoned with. And that is something that I could have never anticipated when I went in to audition for my little three-episode arc."

11.On The West Wing, Donna Moss was initially written as a recurring character with only a few lines. However, series creator Aaron Sorkin "saw something in the chemistry" between Janel Moloney and Bradley Whitford "very early on." According to Janel, the scene that sparked Aaron's idea for their slow-burn romance was in the pilot, when Donna barged into Josh Lyman's office to check on him.

  NBC / Via HBO Max
NBC / Via HBO Max

Aaron told the Associated Press, "Every time I talk about getting Donna and Josh together, my partner Tommy [Schlamme] shouts, 'No! Wait another year!'"

12.On ER, Carol Hathaway was originally going to die in the pilot. Julianna Margulies was about to sign onto a "bad sitcom," but George Clooney called her and told her, "I overheard that your character tested well, and if I were you, I wouldn't take another job because I think they're gonna bring you back to life." She took his advice, and Carol went on to marry Dr. Doug Ross.

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On Late Night with Seth Meyers, Julianna said, "Honestly, I owe my career to George Clooney. ... He brought me back to life."

13.On Pretty Little Liars, showrunner Marlene King "had one episode where [the writers] thought it would be interesting if Spencer [Hastings] volunteers to tutor Toby [Cavanaugh] in French so she could get information," but then the chemistry between Troian Bellisario and Keegan Allen "was so interesting, [they] wanted to push it toward a romantic place." In the books, Toby died, but on the show, he ended up with Spencer.

  Freeform / Via HBO Max
Freeform / Via HBO Max

Marlene told Vulture, "When it comes to the mystery stories, they're plotted out very carefully very far in advance, and we don't waver from those stories. We do not deviate from them at all. When it comes to the character arcs, and the emotional paths that the girls and the guys take along the way, we kind of take that as it comes. We let the girls dictate that in a way; we see how people connect [and if they do], we'll play that longer. So we're flexible when it comes to the emotional arcs and rigid about the mystery arcs."

14.On Grey's Anatomy, Jessica Capshaw signed on to play Dr. Arizona Roberts for three episodes. However, showrunner Shonda Rhimes "had this idea that [her] character could present a storyline for Callie [Torres]." Fans responded excitedly to Jessica's chemistry with Sara Ramirez.

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Jessica told NBC Out, "It was an experiment to see what worked. It just kind of kept working."

15.And finally, on Gilmore Girls, Luke Danes was originally written as a woman named Daisy. The network told series creator Amy Sherman-Palladino that the show "needed another guy," so she "literally just took a character and changed the name, didn't even change any of the dialogue because [she's] that lazy." However, the undeniable chemistry between Scott Patterson and Lauren Graham elevated Luke from simply the coffee shop owner to Lorelai's true love. Amy knew there was something special between them during "the episode where they were in the market and Lorelai's spying on Dean [and] Luke was there, and they had this scene that didn't mean anything."

  The WB / Via Netflix
The WB / Via Netflix

Lauren told Entertainment Weekly, "It didn’t seem like, 'Oh this is the definite love interest.' It's just this funny, weird chemistry that we had in terms of being complete opposites and also this built-in conflict of he has the thing she wants — which is coffee. But in those first couple years, I had a bunch of different dates. Jon Hamm was one of them. We had Max Medina. It could've gone in any number of ways. It was just something about the two of those characters together that they kept going back to and then it kept growing."