How did Sergio meet Gideon in the novel, Nine, Ten: A September 11 Story?

Sergio met Gideon, a fireman, when Sergio jumped the turnstile to ride the subway after his MetroCard did not work. At first, Sergio thought Gideon was no one of any importance because he was just a fireman. However, Sergio was impressed with Gideon’s authority and skills when he tended to an injured man in the subway car. The two became friends when Gideon called on Sergio to help him and took him out for dinner later.