Losing a child is a pain no parent should ever have to endure—a heartbreak Sylvester Stallone experienced in 2012 when his eldest son, Sage Stallone, passed away at just 36 years old. Sage, who had acted alongside his father in Rocky V, was a passionate filmmaker and shared his dad’s deep love for cinema.

Sage was born during Stallone’s first marriage to Sasha Czack. Not long before his death, Sage had undergone dental surgery to remove five teeth. Despite his mother’s concerns about the procedure and the use of painkillers, Sage went ahead with it. Two weeks later, he died from a heart attack caused by atherosclerosis. Although painkillers were found in his system, the coroner ruled out both overdose and suicide. The tragic loss shook Stallone, who called Sage “the center of our universe.”

Despite early media speculation, Sage was not battling addiction and had actually been making plans for his upcoming wedding.

Stallone, who rose to fame despite a difficult upbringing, leaned heavily on his family to get through the loss. He remains close to his second son, Seargeoh, who is on the autism spectrum, and to his three daughters—Sophia, Sistine, and Scarlet—with his wife, Jennifer Flavin.

Sage’s death left a hole in Stallone’s heart, but he continues to honor his son’s memory and finds strength in the love and support of his family.