Lucas starts dating Brooke, though Peyton is clearly in love with him.
The audience finally learns Jake's little secret: he has a daughter.
Lucas cheats on Brooke with Peyton.
Keith and Lucas get in a car accident on the way to pick Karen up from the airport, leaving Lucas in a coma.
Nathan strips for the annual "Boy Toy" charity auction.
Nathan and Haley elope.
Dan suffers a heart attack after discovering that his wife Deb slept with his brother Keith.
We find out Jules is working for Dan as part of his revenge scheme on his brother, Keith.
Haley leaves Tree Hill to go on tour with Chris Keller.
Nathan crashes a race car while visiting his Uncle Cooper.
Dan is drugged while his car dealership is set on fire with him still inside.
Both the basketball teams and the cheerleading squads get into a rumble during "Midnight Madness."
The school shooting episode leaves a student dead from suicide and Peyton injured from a bullet to the leg. Dan shoots his own brother Keith in the chest, killing him.
Nathan and Haley get married again, but their wedding day ends in tragedy when a car accident leaves Nathan, Uncle Cooper and Rachel's lives in danger.
Peyton is attacked by someone posing as her brother ("Psycho Derek"), but her real brother saves her in the nick of time.
Haley tells Nathan she's pregnant, seconds after he tells her he's been offered a basketball scholarship to Duke.
Lucas finally admits his love for Peyton after the Ravens win the state championship.
Haley is run over by Daunte, who was aiming for her husband Nathan. Lucas suffers a heart attack after arriving at the scene of the accident.
Psych Derek returns and holds Peyton and Brooke hostage in Peyton's own house.
Haley goes into labor while giving her Valedictorian speech.
Dan confesses to murdering his brother Keith and goes to jail.
Four years later, Nathan is in a wheelchair and battling alcoholism.
Lindsay leaves Lucas at the altar after realizing he's in love with Peyton.
It's revealed that it was Peyton that Lucas called from the airport and proposed to.