Season 1 Brooke Davis is shown to be a rich, popular, outgoing, and promiscuous head cheerleader at Tree Hill High. She first appears in 1x02, as Peyton Sawyer's (Hilarie Burton) best friend since the latter's mom death when they were nine. Initially, her crazy antics are responsible for a lot of comic relief in the show.
She takes a liking to Lucas Scott (Chad Michael Murray), and starts hitting on him in her usual way. Lucas takes it in his stride, and does not feel that Brooke wants to be in a relationship with him. One night, after Peyton is drugged at a party, Brooke calls Lucas for help....
One Tree Hill . Season 6 . Premiere. Episode 1 . Touch Me I'm Going To Scream, Part 1
This where Haley comes home and asks where Deb is, and Nathan tells her he found her swimming topless in the pool, and about Peyton & Lucas.