Here's a breakdown:
Best Friends:
* Blair Waldorf and Serena van der Woodsen: They are the heart of the show, constantly shifting between best friend and rival. They support each other through thick and thin, but also often betray and compete with each other.
* Chuck Bass and Nate Archibald: While not always showing it, their rivalry often stemmed from competition for Serena's attention. Deep down, they have a strong bond, especially as Chuck matures.
* Jenny Humphrey and Vanessa Abrams: While their friendship is tested by their contrasting paths, their initial bond is undeniable.
Main Rivals:
* Blair Waldorf and Serena van der Woodsen: They compete for everything: popularity, boys, and social dominance. Their rivalry is central to the show and drives a lot of the drama.
* Blair Waldorf and Chuck Bass: They are both ruthless and ambitious, which leads to constant competition. They also have a complex, love-hate relationship.
* Serena van der Woodsen and Georgina Sparks: Their rivalry is fueled by Georgina's manipulative nature and Serena's desire to hide her past.
Ultimately:
The show plays with the lines between friendship and rivalry, making it impossible to definitively label one person as the best friend or main rival of another. The dynamics between the characters are constantly evolving, and their relationships are what make Gossip Girl so compelling.