The Fates (also known as The Moirai) are the three white-robed personifications of destiny in Greek mythology. Their Roman counterparts are the Parcae or Fata. The Greek word Moira literally means part or portion and by extension one's portion in life or destiny. They controlled the metaphorical thread of life for every living thing from birth to death.
When their school year ended, Percy Jackson and Grover Underwood were taking a bus from Yancy Academy back to Manhattan, the bus broke down on a stretch of country road. On the other side of the highway was an old-fashioned fruit stand, occupied by the Three Fates, as three old ladies sitting in rocking chairs, knitting a huge pair of socks using an electric blue yarn. The lady on the right and left were each knitting a sock, while the middle one was holding the yarn. Percy described them as ancient, with their silver hair tied back in a white bandanna, wearing cotton dresses and having bony arms.
They were looking right at Percy when the middle one took out her scissors, a large, gold and silver long bladed one similar to shears, and cut the yarn. The resulting snip could be heard over the four lanes of traffic. They balled up their yarn afterwards. Grover, seeing this, was extremely scared, thinking the yarn was Percy's lifeline, and that he was going to die soon.
The Fates were mentioned by Artemis while Zoë Nightshade was dying, Percy asked the goddess why she could not heal Zoë of her wounds. Artemis replied that life is a fragile thing and if the Fates will the string to be cut, there is little she can do but try. Percy also says during the council of the gods that "controlling the prophecies never works" because prophecies are what the Fates have decreed.
Right before Percy is about to decide if he will stay with Calypso or go back to Camp Half-Blood, Calypso explains the nature of her punishment. Every few hundred years, the Fates send her someone that can never stay for long and will always be someone that she can't help falling in love with. She claims the Fates are cruel as they always send someone that would break her heart in the end. Right after she offers Percy the chance to stay, she says that she wasn't going to but did it anyway, something that the Fates may have known she would always do.
The Three Fates appeared on Olympus to take away Luke Castellan's body after the end of the Second Olympian War. One of them looked at Percy and he saw his life flash by. She said "It is done", holding up the snippet of blue yarn. Percy knew instantly that it was the same blue lifeline that he had saw them snip four years ago. Percy at first thought that it was his lifeline, but then realizes that it was Luke's, the life that had to be sacrificed to set things right. After Luke's body was taken away, Hermes says that "no one can tamper with fate, not even a god".
- Control Over Fate: They all possess power beyond the Olympian gods and Titans since it was stated that not even a god can defy fate. Hence, they can change and control the destinies of both mortals, gods and even other beings as well, to the point that even Zeus is afraid of them; this fear is so extreme that it resulted in his divorce with Themis.
- Prowess in Battle: The Fates defeated two giants in the Giant War, Agrios and Thoon, both of whom they clubbed to death. Jason, who witnessed them do it again in The Blood of Olympus, describes it as a very fearsome sight.
- Thread of Life: Each fate had a significant job with the thread of life:
- Clotho: Spins the thread of life from her distaff onto her spindle.
- Lachesis: Measures the thread of life with her rod.
- Atropos: Cuts the thread of life; she chooses the manner of a person's death.
- Rick Riordan chose two different versions of the Fates' parentage for the Camp Half-Blood books. According to Percy Jackson's Greek Gods, the Fates are the children of Zeus and Themis. But in the House of Hades, Nyx claimed to be the mother of the Fates.
- The Fates fought in the first war against the Gigantes clubbing Agrios and Thoon to death with Bronze Maces just as they did in The Blood of Olympus.
- Their Egyptian equivalents are the Hemsut.
- Their Norse equivalents are the Norns.