Theseus became heir to the Athenian throne. He had many heroic feats. Two examples would be, defeating a plot against his father and destroying a Minotaur.
Athens was a tribute state to Crete under the leadership of King Minos, who demanded a tribute of 14 people each year to feed to his Minotaur. The Minotaur was a monster with the body of a man and the head of a bull housed within a great labyrinth. Theseus volunteered to be one of the tributes and King Aegeus reluctantly agreed. When he arrivied in Crete, Ariadne, the daughter of King Minos, fell in love with Theseus and agreed to help him kill the Minotaur if he agreed to take her with him when he left. She then gave him a length of string which he tied to the doors of the labyrinth and let out behind him as he searched for the Minotaur, which he found in the center of the labyrinth, and killed the Minotaur.