Theseus was the son of either Poseidon or Augeas and the son of Athera.
Augeas put a sword and shoes under a rock for when Theseus was old enough he could move the rock and come visit his father. After a while Theseus was old enough to move the rock and go to his father. And also slayed many monsters along the way.
Theseus finally visited his father, and went off to slay the Minotaur and he promised his father that if he survived he would sail back with white sails. After arriving at Crete to slay the Minotaur.
When Theseus arrived King Minos's daughter fell in love with him and gave him some string so he wouldn't get lost. After slaying the Minotaur Theseus left without changing the sails to white, and leaving King Minos's daughter behind.
When sailing back, Aegeas saw the black sails and out of grief of his sons 'death' he flung himself off of a cliff. and That's the story of Theseus the hero.