You know what they say: Veronica Mars, she's a marshmallow.

Can you believe it's been almost 20 years since Kristen Bell made her debut as the titular character on Veronica Mars, becoming a household name and cementing Veronica's status as one of TV's most badass and sarcastic heroines?

Bell, who turns 43 on July 18, would go on to play the witty yet vulnerable teen private investigator in three seasons on The WB, one fan-funded movie in 2014 and in a Hulu revival series, proving fans—affectionately known as Marshmallows—could never get enough of Veronica.

But in the initial concept for the show, creator Rob Thomas pictured a completely different actress for the character. And though they went on to become one of TV's most beloved couples, Thomas never considered pairing Veronica with Logan before casting Jason Dohring as Neptune's damaged bad boy. 

Those are just two behind the scenes facts we've uncovered, and, like Veronica, we're sharing the goods from our investigation in honor of Bell's birthday.

So, break out your binoculars and pack your taser as you check out these 15 secrets about Veronica Mars:

1. In the original Veronica Mars script, creator Rob Thomas described the titular teen P.I. as a brunette, young Angelina Jolie-type, but his plans completely changed once he saw Kristen Bell read for the part.

"Kristen was the very first actress I saw and my mind was blown," Thomas recalled at PaleyFest 2014. As he auditioned the next 99 people for the part,  he continued, "I kept thinking, 'Was that first girl as brilliant as I thought she was?'" Clearly, she was.

2. Still, she wasn't the only actress to be brought in to test for the network: She was up against Alona Tal, who would go on to play Meg Manning.

3. Veronica's signature style? It was mostly Bell's doing, with the star telling Vanity Fair, "Rob built her emotional armor in the context of the story. I, along with the prop and costume department, built her physical armor—her leather jacket, her combat boots, her dark-colored wardrobe. Her bag to me is her binky that has all her weapons and tools in it."

4. Teddy Dunn initially read for Veronica's nemesis turned love interest Logan, while Jason Dohring first auditioned for Duncan, Veronica's OG boyfriend. Of course, they would go on to land the opposite parts. 

5. "LoVe" a.k.a. Logan and Veronica? A couple that was never supposed to happen.

 "The truth is, we never had any intention at all for Logan to end up with Veronica," Thomas told GQ. "[Dohring] was hired to be the obligatory psychotic jackass. In the writers' room, sitting around watching dailies, we would all gather around, and it was like, 'We want to watch that. We want to watch those two onscreen together.'" Producer Diane Ruggiero added in an interview with Vanity Fair, "Everyone wanted to write scenes with them. It was like, 'We have to go that way.'"

So the end-game shifted, with Dunn revealing to Vanity Fair of the original plan, "Duncan and Veronica were always meant to be together." 

6. Initially hired to just be a day-player, Ryan Hansen's Dick Casablancas became a series regular and one of the most beloved characters, despite starting off as "'09er dick" in the script. "From what Dan and Rob tell me," Hansen told Vanity Fair, "the hair's why they liked me so much." 

7. When Paris Hilton guest starred in an early season one episode as Logan's rich girlfriend, she had an odd demand on-set: "Rob's assistant had to buy Paris Hilton's Chihuahua French fries, because the Chihuahua ate McDonald's French fries," Ruggiero recalled. "Me, miss animal lover, was like, 'Is that all she's feeding that dog, f--king fries?'"

8. The "biggest surprise" for Thomas early on was Amanda Seyfried's turn as ill-fated Lilly Kane, revealing to GQ that he was blown away by her audition as it was "about 100 times better than anyone else that we saw, she was just spectacular." Seyfried was so good, in fact, that he ended up adding in four times more scenes featuring Lilly than he originally intended.  

9. Season one was built around one main mystery: Who killed Lilly Kane? In the finale, Logan's dad, Aaron Echolls, was revealed as Lilly's killer. While that was always Thomas' plan, he almost had to change it after Harry Hamlin booked a movie that would make him unavailable. Fortunately, Hamlin ended up passing on that project to film Veronica Mars and Thomas never had to use his back-up plan: Duncan. 

10. The recurring role of Vinnie Van Lowe, rival P.I. to Veronica and her dad Keith Mars, was written specifically for Paul Rudd, but after the star's schedule changed, Ken Marino took over the part. Rudd would guest star in season three as a rock star. 

11. While Thomas struggled with the network finding the original pilot script "too dark and creepy," asking him to tone down or take out many lines and plot points, there was one note he is grateful to have followed: In the original version, Veronica discovers her dad Keith (Enrico Colantoni) had been hiding letters her mom had been writing to her. 

"The note from the network was her best friend's dead, she's been raped, her mother abandoned her, her dad lost his job. Can she just have her dad?" Thomas recalled. "It was a really good note." Keith and Veronica would go on to have one of the most adored father-daughter relationships in TV history.

12. Oh, Piz. Brought in as Veronica's new love interest in season three, Chris Lowell revealed Thomas had "warned me out of the gate, 'You will be the least liked character on this show.'" An intense love triangle and shipper debate commenced, with Lowell receiving so much heat that he didn't even expect to be asked to return for the fan-funded movie. 

"Honestly, I legitimately had come to a place where I was ready to accept that I would not be in the film,'" he said at the 2014 Paleyfest event. "But then Rob sent me this email saying, 'Hey, by the way, I think we're gonna make this film. There's actually a role for Piz.' I'm thinking, 'He gets killed. He's the victim.' He's like, 'No, it's actually a substantial part.'" (Spoiler alert: He was still dating Veronica.) 

13. Another man that vocal "LoVe" fans took to online message boards to criticize?  Deputy Leo, played by Max Greenfield. Only slated for one episode, the New Girl actor quickly became a favorite of Thomas and the writers.

Though Thomas read the message boards frequently, taking notes on what fans were reacting to, Leo was one character he refused to change: "Just because the viewers aren't raving about him" he told Salon in 2005, "you know, I'm not going to write him out [of the show] just for that, because I think he's good, I think he makes the show better."

As Greenfield put it to Vanity Fair, "I didn't really serve the story at all, but Rob and Dan were like, 'We really like him. Can we have him pop in and out for no reason at all?'"

14. One romance that never happened was between Veronica and her BFF/sidekick Wallace (Percy Daggs III), though the actor tried to pitch it once, "But the network didn't want to touch it," Daggs told a fan site, "so I didn't push it."

15. Before the Kickstarter campaign brought fans back to Neptune in 2014, Thomas & Co. pitched The CW a 10-minute presentation of what a season four would look like if they picked it up (which ended up on the season three DVD set): It would've followed Veronica as she entered the FBI, with Walton Goggins serving as her mentor. 

"It really was a Hail Mary pass, and the thing that a lot of people don't know is how close it came to succeeding," Thomas told GQ. Alas, The CW decided to cancel the series completely. "I was happy we tried it," Thomas said. "Somebody asked me, 'Are you glad that that didn't go?' And it's impossible to know."

Veronica Mars is streaming on Hulu.