Final answer:
The son of Jupiter and Semele in the Theban cycle is Dionysus, the god of wine, fertility, and festivity in Greek and Roman mythology.
Step-by-step explanation:
The mythical figure from the Theban cycle who was the son of Jupiter (the Roman version of Zeus) and Semele is Dionysus. In mythology, Semele was a mortal woman who was desired by Zeus.
Their union led to the birth of Dionysus, who would become the god of wine, fertility, and festivity in Greek and Roman mythology. The story of his birth includes a tragic turn where Semele perishes, Zeus rescues the unborn Dionysus by sewing him into his thigh until he is ready to be born.
The nature of his birth was remarkable and signifies his role as a deity that would stand between the mortal and divine realms.