Dan Scott is the father of Nathan (James Lafferty) and Lucas Scott (Chad Michael Murray). Nathan and Lucas are only half brothers, but they are the same age as Dan left Lucas' mom and married Nathan's mom. Dan used to be a basketball star so he pushes Nathan to join the team. Lucas, however, grew up without Dan in his life. Unlike his brother he is able to join the basketball team and enjoy his experience because his dad is not pushing it on him.
Dan ran for Mayor of Tree Hill and won the election. At one point someone tried to kill him by drugging him and setting his car dealership on fire while he was inside. Even though Lucas isn't Dan's biggest fan he ran into the dealership and saved his father's life by dragging him out of the fire. Dan's wife tried to kill him because she knew he was not a good person and he basically made her life miserable.
When there is a shooting at the school, Dan goes into the school to help. He finds his brother Keith (Craig Sheffer), with the shooter Jimmy Edwards (Colin Fickes), who has committed suicide. Dan picks up the gun and shoots his brother letting the town think that Jimmy is the one who killed Keith. Dan had always been jealous of Keith for several reasons, including Keith's relationship with Lucas and his mom.
Dan is eventually caught and sent to prison. When he is released many years later, he tries to re-enter his sons' lives, but they are not as receptive as he would hope. He learns that he has a heart condition and spends a great deal of time waiting for a heart transplant.
"I should apologize... but I won't."
"Somewhere along the line, I started hurting the people I care most about, and I can't figure out how to stop."