Frank Zhang's life was tied to a piece of wood. If it burns up, he will die. It was given to him by Juno due to him "having too many gifts." It is supposed to be a huge weakness to balance out Frank's many advantages and gifts.
When Frank was a baby, Juno appeared in front of Emily Zhang and Grandma Zhang while they were sitting with baby Frank in front of the fireplace. The goddess warned them that when Frank's stick, which was currently burning in the fireplace, was consumed, Frank would die. Emily, in a panic, removed the stick from the fire. She and her mother would later wrap the stick in bubble wrap to protect it.
Frank was given the stick shortly before his mother's funeral by his grandmother, who tells him the stick's story. He keeps it with him all the way to Camp Jupiter, and at one point accidentally sets it on fire just by thinking about it. Frank is later told by Iris that he is destined to die holding the stick, watching it burn. At her advice, he confides his secret in Hazel Levesque, and gives her the stick to keep an eye on. The three later arrive in Alaska, and make it to where Thanatos is being held. Thanatos tells them "only the fire of life can break the chains of death." Frank, understanding, takes the stick back from Hazel, and uses the fire to melt Thanatos's chains. He then douses the fire, leaving the stick no bigger than a candy bar. He later gives the stick back to Hazel for safekeeping.
Leo, while stranded on Ogygia, discovers Calypso can weave fire-proof cloth. He requests a small pouch made of the material, which she provides. He demonstrates the fire-proof capabilities to Frank and Hazel. Frank, grateful, decides that it is time for him to carry his own burden, and takes the stick back from Hazel.
By the time of Caligula's Assault on Camp Jupiter, Frank has come to see the firewood as a part of him, however he has become reckless. During the Battle of San Francisco Bay, he ignites the stick to kill Commodus and Caligula. Miraculously, the son of Mars does not die when the stick burns up. He speculates that by taking his fate into his own hands, he broke Juno's curse, so his life is no longer tied to his stick. Apollo suggests that another explanation is that Juno herself intervened to help, stating that although it's quite unlikely, the goddess has always had a soft spot for Frank.
- This idea comes from the myth of Meleager; In Greek mythology, Meleager was a hero and famed host of the Calydonian Boar Hunt. When Meleager was born, the Fates predicted he would only live until a brand, burning in the family hearth, was consumed by fire. Overhearing them, his mother immediately doused and hid the brand. When she found out that Meleager had killed her brother for the love of the huntress Atalanta, she placed the brand upon the fire, thus fulfilling the prophecy and killing Meleager.
- In The Son of Neptune, the goddess Iris told Frank that he would die holding his stick, watching it burn.
- This somewhat came true in The Tyrant’s Tomb, when Frank burns it to take out two of the emperors but services, symbolically dying to free himself of the stick and being reborn to a life not bound to it.