Walter O'Brien (Scorpion)

O'Brien is often described as the stereotypical computer "nerd".[9] He is usually characterized as extremely intelligent, socially inept, and rigidly logical. He regularly displays a lack of emotional intelligence and empathy, preferring to use logic and reasoning to “fix” the world around him. His beyond genius-level IQ allows him to solve problems that other people could not, but it also diminishes his ability to relate and empathize with other people. When O'Brien feels like he is failing at a task, he panics and starts to lash out at those around him.

Like his friends in team Scorpion, O'Brien is scientifically inclined and gifted with computers. He sometimes shows empathy, particularly towards the empathetic waitress Paige Dineen, who coaches O'Brien and his Scorpion team as they attempt to mature emotionally.

O'Brien forms a relationship with Paige, played by Katharine McPhee, a struggling waitress when she meets O'Brien and his team in the pilot episode. She works to help O'Brien and his team interact with normal people and learns from O'Brien that her son is not challenged but really a genius. She also seems to have feelings for O'Brien, but has trouble dealing with them due to Walter's not believing that love and emotion are real. The two eventually begin a romantic relationship.

In the pilot, Agent Cabe Gallo recruits O'Brien and his team to help the United States government fix a serious air traffic control problem and then asks them to become a liaison team to tackle difficult missions that arise that the main government organizations do not have the manpower or technological prowess to handle, like stolen nuclear weapons and similar issues. He was the one who brought Walter over from Ireland and then worked with him for several years. They had a falling out when O'Brien was 16 over civilian casualties during an attack on Iraq using a computer program that Walter had created for humanitarian purposes.

O'Brien's sister, Megan O'Brien (deceased), who he was very close to, and a mother and father, who he is less close to, though his sister's death helped him try to mend their burnt bridges. He also grew up in Callan, Ireland, where his sister got him out of trouble when he was too much of a smart aleck.

O'Brien's relationship with his team is a little rocky, owing to his low EQ panics and rages, which happen usually whenever they run into trouble in a mission. But thankfully, Paige helps calm him down and keep him from going too far and to stay productive. But even after this, his team members still respect him as a leader of them and like him as a friend, even when he can be a little short sighted and thinks of the world in only logical steps and explainable equations as opposed to human unpredictability and emotions.