The Curse of Achilles is a power and a curse that a person can acquire when they bathe in the River Styx.
Thetis, in an attempt to make her son, Achilles, immortal, dipped him in the River Styx as an infant, holding him by the heel as she had dreamt of his death some time before. The attempt was unsuccessful, however, as Thetis' husband, Peleus, ignorantly interrupted the ritual and took his son away, for he believed that Thetis was hurting the baby. Angered, Thetis returned to the sea, leaving both her husband and son, and although he remained mortal, Achilles himself was rendered invulnerable and he grew up to become the greatest Achaean warrior, even killing the Trojan prince Hector during the Trojan War. Despite this, Achilles was himself slain when an arrow fired by Paris struck his heel, the one place on his body that was still vulnerable.
In The Last Olympian, Percy Jackson bathes in the River Styx on Nico's insistence; in the midst of the impending battle against Kronos, the odds appeared to be heavily against Olympus and so Percy resolves to take on the Curse of Achilles in order to compensate. This proves to be effective as Kronos and his forces suffered hundreds of casualties while Camp Half-Blood sustained only sixteen in the final battle.
The curse is named after Achilles, the Ancient Greek hero, who was famous for his invulnerability. When one bathes in the River Styx, they will be granted the power to remain uninjured by any means. However, they will always have one weak spot and if this weak spot is injured even in the slightest, the person will die. For Percy, it was on the back. For Achilles, it was on his heel and for Luke, it was on his armpit. For a person to successfully receive this curse, he must earn his parent's blessing before bathing in the river or it would kill whoever enters its shores.
When one bathes in it, the person must envision one thing that ties them to the living. They also must imagine a single spot on their body that will be vulnerable and a rope tying them to the mortal plane. If they do not do this they will turn into ash and be forever lost in the River Styx. Though not proven, the thing a person usually envisions is often someone close. An example of this is when Percy bathes in the Styx, he envisioned Annabeth Chase, the girl he loves.
Exposure to the water of the Tiber negates the curse permanently, because it is a Greek blessing/curse that could not be retained in territory belonging to the Romans (i.e. Camp Jupiter), the enemies of the Greeks, according to Juno. We see an example of this when Percy loses the curse in The Son of Neptune.
Anyone who bears the Curse of Achilles is nearly invulnerable, except in one weak point. They also get highly increased strength, speed, agility, reflexes, endurance, and fighting skills, also linking to their abilities, making it less tiresome to use immense powers. One such example of this is Percy, who was powerful enough to defeat Hades, Hyperion, a hundred skeletal warriors created by Hades, and a large fraction of the Titan army equivalent to hundreds of monsters after taking on the curse. The curse also allowed Achilles to slay a large amount of Trojans and Amazons during the Trojan War.
The most obvious weakness is the mortal spot the person chooses, as it remains the only place that can be injured. If this spot is even slightly injured, the person will die immediately.
The less obvious weakness is a secondary function - in addition to gaining invulnerability, bearers of the curse also gain extreme physical prowess, such as heightened strength and reflexes, and a body that almost automatically fights. However, this places an enormous amount of stress on one's body, as their enhanced fighting skills means that they expend energy at a much faster rate, requiring a bearer of the curse to be careful not to overexert himself. Chiron says that Achilles himself took about twenty naps a day, later stating that when Achilles wasn't fighting, he was either sleeping or eating.
It is also mentioned that a bearer of the curse will have certain emotions or behaviours enhanced, normally having to do with their fatal flaw. One other major weakness is that while bearers of the curse are immune to injury, they can still be killed by other means, as their body is still mortal:
- Asphyxiation (e.g. drowning, choking)
- Diseases (heart attack, strokes, cancer,etc.)
- Electrocution (during The Last Olympian, the river gods threaten to kill Percy Jackson with electric power cords).
- Burning (during The Last Olympian, when Kronos was trying to get his scythe, he was burned by Hestia).
- Gods' true form (the bearer is invulnerable and not immortal. So a god's divine form will still kill him or her).
- Gods' wrath (while a bearer is invulnerable, a god can still kill them with a snap of a finger as in The Last Olympian, Percy was afraid of bringing the entire fighting force to Mt. Olympus, afraid that the gods will be angry and he would get "blasted to bits", and since gods are capable of killing mortals with a thought, this is very probable. )
- Overexhaustion (Chiron mentioned that Achilles had to sleep "twenty times" a day, so if the bearer of the curse is constantly fighting for too long, then they can burn themselves out, most likely the bearer hasn’t adapted to the curse.)
|Luke Castellan||Below the left armpit|
|Percy Jackson||Small of the back, opposite the navel (formerly)|
- When Percy was trying to pick his Achilles' heel, he said he didn't want to pick an embarrassing spot like his armpit. Later, when Luke asks for Annabeth's knife so he can kill himself, his Achilles' heel is revealed to be under his left armpit. However, Percy says this was a good idea as it can be hard to hit someone's armpit.
- Apparently, while being invulnerable, the bearer can still feel pain to a certain extent. Examples include when Percy was fighting the giant Cacus, and was very disoriented after being hit into a wall, almost knocking him out. Another time, Percy cried in pain when jumping onto Blackjack. Also Kronos, despite having Luke bathe in River Styx, was still burned by Hestia when he tried to grab his scythe. However, the amount of pain felt will be greatly reduced.
- In the series, the only known bearer to have their weak spot involuntarily struck was Percy, when Ethan Nakamura inadvertently attacked him from behind. Although unintentional, Nakamura was able to deduce where Percy's weakness was, but never got another chance to fully attack it.
- The curse can apparently be removed when entering certain magical places connected to Rome, as the curse is a Greek blessing. One of these places is the Tiber River at Camp Jupiter, which has the ability to wash the curse away. Percy is the only known demigod to lose it without being killed.
- Your Achilles tendon is named after Achilles, due to it being close to the heel.
- A common quote is someone's 'Achilles Heel,' which is someone's weakness, named after Achilles because of his weak heel.
- All the known bearers of the curse in both the series and mythology were male. No female has ever been known to bear the curse.
- The curse of Achilles, despite its Greek origin, is quite similar to the invulnerability of the Norse god Baldr, who also had only one fatal weakness, and, according to some myths, also killed with an arrow of mistletoe.
- Achilles being invulnerable was a later addition to the myth, the story of Thetis dipping an infant Achilles into the River Styx and rendering her son invulnerable first appearing in an unfinished epic poem titled Achilleid, written by the Roman poet Statius between AD 94 and 96.