Dionysus is the Greek god of Wine and Ritual Madness. He is the son of Zeus and Semele, a beautiful princess. She was killed by Zeus's jealous wife, Hera. Who convinced her to ask to see him in his true form, when Semele asked to see Zeus in his all of his divine glory, she burned to a crisp as of seeing lord Zeus in his Olympian state.
He is married to Ariadne, who was the daughter of King Minos, the king of Crete. After Theseus abandoned her, Dionysus mad her his wife.
Dionysus helps run Camp Half-Blood.