Charmspeak is a type of hypnotism or persuasion in which it allows the speaker to convince someone else to do or get whatever they want. The strength of the command depends on the tone and the emotion of the charmspeaker's voice, as well as their skill with it. Eventually, charmspeak wears off and the person has no recollection of why they did what they were commanded to do. For those children of Aphrodite blessed with this gift, they may not realize that they are using this ability, usually not trying to put any power into their words, though they can still charmspeak other people. This happened often with Piper McLean, who didn't realize at first what she was doing. She would ask for things and people would give it to her, which lead to her father, Tristan McLean, defining her as a kleptomaniac, as she just kept stealing bigger things, like a car. In The House of Hades, Piper wakes up Festus, who was shut down for upgrading, using charmspeak.
The only known demigods, as of now, to possess this power are Piper and Drew Tanaka. Any other demigods with this particular gift are yet to be introduced into the series. Circe has charmspeak powers and taught it to her niece, Medea (as stated in The Lost Hero). Circe herself had seemingly used charmspeak in The Sea of Monsters, charmspeaking Percy. A charmspeaker can reverse other people being charmspoken if they are skilled enough.
Charmspeak can be negated through a number of ways. It has a diminished effect on other charmspeakers. It is neutralized by the power of gold (though not necessarily by gold itself, but rather the magical ability to turn people to gold). People with strong wills or intentions are unaffected, and the more powerful the being, the stronger their resistance. If someone is aware of a persons ability to charmspeak, then it will have a reduced effect as they will be on guard in case they are the subject to it. Also, beings of the same gender tend to have some resistance to charmspeak, as Ma Gasket wasn't affected by Piper's power, although her two sons were. Piper also wasn't able to charmspeak Khione, because "wind gods are creatures of chaos."
Circe uses a form of charmspeak on Percy. As Percy listens to her, he feels bad that he does not meet her standards in physical appearance and was willing to do almost anything to meet the said standards. This eventually leads to him drinking a potion that turns him into a guinea pig.
Growing up, Piper McLean would unknowingly use this ability on people in order to gain the attention of her father. The people she used it on would give her whatever she asked for, but would eventually come to their senses. They would feel so foolish for just giving her things, that they would instead call the cops and report it as theft. This eventually lead to her being sent to the Wilderness School, a school for troubled kids.
Eventually, Piper made it to Camp Half-Blood, where she met a girl named Drew, who was the current head of the Aphrodite cabin. Drew would use her charmspeak ability to control the other members of her cabin and occasionally others as well. During the campfire, Jason was tasked with picking a child of Aphrodite for his quest. Drew used this ability to get everyone to agree that she should be on the quest. Piper also claimed that she should go, as Hera had contacted her. Piper unknowingly was using charmspeak and the crowd started swaying back and forth between Drew and Piper until Piper was claimed.
When Piper was given a room at the cabin, Mitchell and Lacy explained exactly what charmspeak was and how Drew had used it to take complete control of their cabin. Piper had been the first to stand up to her as she was able to resist Drew's ability. However, the other campers talked about how Drew would use her ability to get them to do embarrassing things in front of the camp as a form of punishment.
While Piper was on the quest, she became much more skilled with her ability. She almost managed to get two cyclopes to release her when she was captured, if it wasn't for Ma Gasket, who saw through the trick and called Piper "Venus spawn". However, Leo Valdez managed to set them free.
When the group entered Medea's shopping mall, Medea used her ability to charmspeak to get Jason and Leo to shop around the store. They became quickly drawn in by her products, including potions that could kill someone instantly and a chair made by Hephaestus that had trapped Hera previously. Piper was able to resist Medea's charmspeak, but still felt the effects as Medea had perfected the art. While Piper tried her hardest to cancel out Medea's charmspeak, she just wasn't strong enough to do so. It wasn't until Medea told Jason and Leo to kill each other that Piper poured all her power into her voice, canceling out Medea's charmspeak.
When arriving to save Piper's dad, Piper was furious that Enceladus had threatened to kill her friends, so she used her voice that carried across the clearing. She commanded that the Earthborn wouldn't hurt the ones she cared about, and it seemed to work until Enceladus ordered them to attack, but even then they were hesitant. Later, Piper used charmspeak to get a helicopter pilot to fly them away from Mount Diablo, and later to give them her helicopter.
After arriving at the Wolf House, Piper used her charmspeak to try and get Gaea to go back to sleep while Leo tried and cut the cage. Her voice caused nearby monsters and wolves to fall asleep. After Hera was freed and unleashed her true form, Jason saw it and almost died. Piper thought she saw him take a breath and used her charmspeak to wake him up.
Piper is seen on the Argo II, practicing her speech, nearly charmspeaking Annabeth Chase into putting her knife down and chatting. She also used her charmspeak against the Roman demigods when they attacked her and Jason to stall them and the eidolons that were possessing Jason Grace, Percy Jackson, and Leo Valdez, to get them out of the boys' bodies. Charmspeak is also used later in the start of the book when Percy Jackson and Jason Grace fight with each other till they are killed but are stopped by Piper when she used Charmspeak.
Annabeth mentions that the Empousai are able to charmspeak. Piper also stops Jason from crashing to the ground after he was flying and asleep by waking him up and flying away before he impacted with the ground. Piper realizes the secret of charmspeak is a lot like using the Mist. When Khoine and her half-brothers freeze everyone on the ship and send Leo flying, Piper uses her charmspeak to anger Khoine and to wake Festus up. The charmspeaker has to push the intended target to do the things they wanted to do, not the charmspeaker and the user that is manipulating the Mist has to make the intended targets see what they want to see. Piper charmspeaks the monsters to fall in the opening in the ground and the Empousai counter it. Piper then charmspeaks the Empousai to fight each other by saying that they insulted each other.
During the final battle against Gaea, once Festus and Jason Grace lift her high in the air, Piper uses her charmspeak ability to put her to sleep. While it requires her to get very close to her, it works and it allows Leo Valdez to scatter and defeat Gaea once and for all.
- It can be used on mortals, demigods, monsters, spirits, Titans, and even gods (though powerful deities are more resistant to it).
- Although it is said to be a power of Aphrodite's children, beings with magical abilities or Loki's children are also able to use it.
- Oaths made under charmspeak are valid and must be obeyed, despite the promise being made against their will.
- However, Annabeth does claim in The Lost Hero that Hermes can be "very convincing", though whether or not this is via charmspeak is unknown.
- Althought Hermes is just very skilled in negotiation and argumentation, as he demonstrated in Percy Jackson's Greek Gods when he negotiated with Apollo for he not kill him and being capable of trade with Apollo the shepherd's pipe for his golden staff, sword and knowledge of the art of prophecy (although he can't teach the last).
- A case could also be made that children of Athena may have this ability, as Athena herself has been able to talk her way out of trouble even with her Temperamental father even during the rebellion. As the Goddess of the Arts and Wisdom, any argument she or her children make would be logical, passionate and sophisticatedly beautiful. While not driven by love, it would be just as potent.