Denis Leary found that the intense emotional spectrum experienced by firefighters in the wake of the September 11 attacks was pivotal in shaping his acclaimed FX series, "Rescue Me." The show, which premiered in 2004 and ran for seven seasons, explored themes of grief, survivor's guilt, and the coping mechanisms of New York City firefighters.

Leary described witnessing FDNY firefighters navigate profound sorrow and sudden bursts of laughter within their firehouses in the months following 9/11. He recalled spending time with firefighters who were sifting through the debris at Ground Zero, known as "The Pile." He observed a moment where a firefighter, overcome with grief after finding a piece of a friend, could barely speak. Yet, approximately 20 minutes later, the same group was laughing together.

"We’re going to make a show where people are on the edge of their seat watching an action sequence involving fire," Leary told The New York Post. "And then the next minute they’re crying because they’re so sad, and then the minute after that, they’re laughing their a---s off."

This observation of emotional whiplash became a central tenet of "Rescue Me." The series starred Leary as Tommy Gavin, a firefighter grappling with personal turmoil and the trauma of 9/11. The show aimed to blend intense action sequences with the harsh realities of loss and the dark humor that often emerged in such environments.

Leary and co-creator Peter Tolan drew heavily on the real-life experiences and stories shared by FDNY members and firefighting consultants. "We had so much information on a daily basis, not just comedically, I’m talking about dramatically," Leary said. "All the ideas for our fires came basically from experiences those guys had."

Leary's connection to the fire service was personal even before 9/11. His cousin and close friend, Jeremiah Lucey, died with five other Worcester firefighters in a 1999 warehouse fire. This event led him to establish the Leary Firefighters Foundation in 2000, which expanded its focus after the 9/11 attacks.

Tolan reflected on the delicate balance of portraying such a sensitive tragedy. "When you know that, you always have to sort of be vigilant to how far am I going and is it too soon to do this?" he said. "But that's the human experience. That is what happens, that is the most pure essence of how people move forward in their lives – is at a certain point, they're able to laugh."

The show's raw portrayal of the firefighters' lives, including their struggles with alcoholism and family issues, resonated with many, earning positive feedback from younger firefighters who felt the show captured their reality. Despite some initial skepticism in Hollywood about incorporating comedy into a post-9/11 narrative, Leary maintained that laughter would be more crucial than ever for public healing.

"Rescue Me" premiered on FX on July 21, 2004, and concluded its run on September 7, 2011.