3. Seth declares his love for Summer in front of the entire school (The O.C, Episode 1.20)
3. Seth declares his love for Summer in front of the entire school (The O.C, Episode 1.20)
Part three of my countdown focuses on a fairly new couple and one that still leaves me feeling heartbroken.
6. Sophia Bush (Brooke, One Tree Hill) and James Lafferty (Nathan, One Tree Hill)

Reports that these two are currently dating started circulating in late 2007 and continue still to this day, though neither has commented publicly about it.
5. Rachel Bilson (Summer, The O.C.) and Adam Brody (Seth, The O.C.)

Bilson and Brody began dating not long after The O.C. debuted in 2003. Their characters had an on-off relationship throughout the series, and the couple themselves broke up towards the end of 2006 (though fans were strongly rooting for them!). During their relationship, they lived together and co-owned two dogs. From a New York Post article: “They say, ‘Don’t date your co-star,’ but that’s who you’re around,” says Rachel. “If you’re in an office, and you see someone every day and you click well, you’ll start dating. It’s the same thing.” The two lived together, and after their breakup in December 2006, they divided belongings and dogs—Adam took pit bull Penny Lane, and Rachel walked away with Thurmen. “Oh yeah, during the divorce, that was a given.”
“We think we had good success on [our first series] “The O.C.”, for example, with the Seth and Summer storyline, where they were really together as a couple for the vast majority of the show. We told stories where they were having issues and they were having obstacles, but in the context of them as a couple. So it’s not necessarily the case that once a couple comes together, they stop being interesting or stop being able to generate story.”
Sorry Adam Brody fans!
Rachel Bilson (Summer, The O.C.) is engaged to actor Hayden Christensen.
Brody (Seth, The O.C.) and Bilson broke up in 2006 after dating for three years.
SUMMER ROBERTS (The O.C.)
Who She Was: A narrow-minded stuck-up bimbo focused on tanning, shopping and partying.

Who She Became: When Summer began college at Brown her focus changed to activism. She completely changed her lifestyle by protesting injustices and taking a job with a global environment organization.
NATHAN SCOTT (One Tree Hill)
Who He Was: The school’s most popular basketball player with a big-man-on-campus attitude and a reckless lifestyle.

Who He Became: Nathan continued to struggle with his temper but softened significantly through his relationship with Haley and his dedication to his young son, Jamie.
Come back tomorrow for one last character transformation!
MONDAY: BEVERLY HILLS, 90210
YESTERDAY: DAWSON’S CREEK
TODAY: THE O.C.
LUKE-MARISSA-RYAN
How It Started: When bad boy Ryan moves next door, Marissa is instantly drawn to him even though she’s still dating her longtime boyfriend–and Ryan’s future enemy–Luke.
How It Ended: After Luke cheats on her, Marissa ends their relationship. Ryan and Marissa start dating soon after.
Key Episodes: 1.2, 1.4-1.9, 1.12,
YouTube Evidence: Ryan/Marissa/Luke–My Girl’s Ex-Boyfriend
THERESA-RYAN-MARISSA
How It Started: Theresa’s relationship with Ryan abruptly ends when he leaves Chino and moves into Marissa’s neighborhood. After a one-night-stand while he and Marissa are broken up, Theresa becomes pregnant and Ryan moves back to Chino to be with her in the first season finale.
How It Ended: In the second season premiere, Theresa tells Ryan she lost the baby, so he goes back to The O.C. and Marissa.
Key Episodes: 1.11, 1.20, 1.26-1.27, 2.1-2.2
YouTube Evidence: The O.C.: Look After You
ANNA-SETH-SUMMER
How It Started: Since he sees no future with his life-long crush Summer, Seth begins seeing Anna. This makes Summer realize her feelings for Seth, and he becomes torn between the two girls.
How It Ended: Just when it seems Seth has finally chosen Anna, he realizes Summer will always have his heart and commits to her. The relationship is tested again in the third season when Seth and Anna run into each other. But this time Anna actually works to keep Seth and Summer together.
Key Episodes: 1.4, 1.9-1.21, 3.22-3.23
YouTube Evidence: The O.C. Anna, Seth + Summer; The O.C.’s Love Triangle–Seth, Anna & Summer!
SETH-SUMMER-ZACH
How It Started: After disappearing and leaving her heart-broken in the first season finale, Seth returns to town to find out that Summer’s moved on to Zach. He then begins a series of attempts at winning her back.
How It Ended: Summer resists Seth’s advances and continues her relationship with Zach. When Zach and Seth team up to publish his comic book Atomic County, Summer is caught in the middle. Just as she’s about to go with Zach on a trip to Italy, Summer realizes she belongs with Seth and they reunite.
Key Episodes: 2.1-2.5, 2.10-2.14, 2.17-2.19, 2.21-2.23
YouTube Evidence: All or Nothing–Seth/Summer/Zach; The Way I Loved You–Summer/Seth/Zach
OTHER TRIANGLES TO CONSIDER
Ryan-Marissa-Oliver
Ryan-Theresa-Eddie
Kirsten-Sandy-Rebecca
Sandy-Kirsten-Carter
Ryan-Marissa-Johnny
Ryan-Tayl0r-Henri Michel
Bullit-Julie-Frank