|“||Oh, did you expect me to play fair? I am the god of love. I am never fair.||”|
–Cupid, The House of Hades
Cupid is the Roman god of desire, affection, and erotic love. He is the son of the goddess Venus and her lover Mars but in some sources, he is the brother of Gaea. Cupid is also known in Latin as Amor ("Love"). His Greek counterpart is Eros.
While looking for Ares' Shield in the Thrill Ride O' Love, Percy Jackson and Annabeth Chase fall into a trap made by Hephaestus. Inside the ride, there are small Cupid statues with sharp arrows aimed at the duo.
Cupid does not make a physical appearance, but he is mentioned. Frank Zhang and Percy think that Thanatos is Cupid. Thanatos states that he is frequently mistaken for Cupid. Thanatos mentions that Death and Love have more in common than people think.
Cupid has Diocletian's scepter and refuses to give Jason Grace and Nico di Angelo the scepter until Nico admits something out loud. Nico attacks the invisible Cupid with Skeleton Warriors until Nico admits that he left Camp Half-Blood for love and admits to liking Percy. After Nico admits his feelings, Cupid turns visible and tells him that the only way to conquer love is to face it.
Cupid is a lean, muscular young man with snowy white wings. He wears a simple white frock and jeans, and has his golden bow and quiver slung over his shoulder. His face is very handsome, but rather harsh as well, and "as difficult to look at as a spotlight." Cupid has shoulder-length straight black hair and blood-red eyes, as if "every valentine in the world were squeezed dry, distilled into one poisonous mixture."
- Amokinesis: As the god of love and desire, Cupid has absolute control and divine authority over love, lust, and desire, but not quite as much as his mother, Venus. Cupid's form of love seems to be harsher and more enforced than Venus's, which might be due to Cupid being a son of Mars.
- Arrows of Romance: Cupid's power over love is usually exercised and enforced through his romantic golden bow and arrow. Anyone struck with Cupid's arrow will instantly be filled with uncontrollable desire and love for another (of Cupid's choice). This will even work on Olympians, shown when Cupid forced Apollo to fall in love with the nymph Daphne in Percy Jackson's Greek Gods. If Cupid's arrows miss a target, they will glow white-hot and explode in a "geyser of flame". However, when it does hit a target, the arrow dissolves, leaving no blood or visible wounds, though Nico's face did depict pain on the impact.
- Coerced Romantic Confession: Cupid can also force anyone to confess their true romantic feelings, and can always tell if the person is lying. The only known one Cupid did this to was Nico di Angelo, with the latter being forced to admit his secret love for Percy Jackson.
- Invisibility: Cupid can render himself invisible in order to assault others unexpectedly.
- French: As a son of Venus and god of love, Cupid is fluent in French due to it being the "language of love".
- Cupid is the brother of Timor and Metus, and the half-brother of Piper and Frank.
- Cupid's form of love seems to be harsher and more enforced than Venus'. This might be due to Cupid being a son of Mars.
- Ultimately, Cupid is the one who finally forces Nico to reveal his secret and passionate love for Percy.
- Cupid is the only god who visibly scares Nico, since the latter is utterly terrified of somehow exposing his homosexuality.
- According to Cupid, his counterpart, Death (Thanatos) can sometimes be kinder.
- "Erotic" comes from the word "Eros", Cupid's Greek name. Hence, Cupid is the god of erotic desires.
- Cupid is also sometimes called Amor in Latin.