Short answers, pulled from the story.
Eros is the Greek god of love and sex. In the earliest sources, such as Hesiod's Theogony written around 700 BC, he is a primordial god who came into existence alongside Chaos, Gaia, and Tartarus. In later myths he is the son of Aphrodite and uses golden and lead arrows to make gods and mortals fall in or out of love.
Eros is the Greek god of love, and Cupid is his Roman equivalent, also called Amor. In early Greek art Eros was depicted as a handsome young adult male, while the later satirical poets transformed him into a blindfolded child. This child figure became the Putto associated with Roman Cupid and eventually the cherub emblem of Valentine's Day.
According to the Roman author Ovid, Eros carried two kinds of arrows. His golden arrows induced a powerful feeling of love in whoever they struck. His lead arrows had the opposite effect, making the target averse to love and filled with repulsion. The two-arrow system is most visible in the myth of Apollo and Daphne.
The myth tells of the quest for love and trust between Eros and the mortal princess Psyche. Aphrodite, jealous of Psyche's beauty, commanded Eros to make her fall in love with the ugliest creature on earth, but Eros fell in love with Psyche himself. After a betrayal of trust and a series of four tasks Aphrodite imposed on Psyche, Zeus transformed Psyche into an immortal. The couple had a daughter named Voluptas, or Hedone, meaning physical pleasure and bliss.
The Lacedaemonians believed that safety and victory in battle depended on the bonds of friendship between soldiers fighting side by side. They sacrificed to Eros before going into combat for this reason. The Cretans held the same practice, offering sacrifices to Eros in their battle lines.
The Greek word eros means desire, and the verb it derives from means to desire or love. The word gives rise to the English term eroticism. The scholar R. S. P. Beekes speculates that the word has a Pre-Greek origin, placing its roots before the Greek language itself.