What role does fate play in the "Aeneid"?
In The Aeneid, fate is the driving force that underscores the actions of Aeneas. Fated to start the Roman Empire by becoming the father of Romulus and Remus, Aeneas must reach Italy. He is destined or fated to reach Italy, his fate which is determined by Jupiter or assisted by Jupiter. Jupiter tells his daughter Venus:
"Know, I have search'd the mystic rolls of Fate:
Thy son (nor is th' appointed season far)"
Who, full of Mars, in time, with kindly throes,
Shall at a birth two goodly boys disclose.
The royal babes a tawny wolf shall drain:
Then Romulus his grandsire's throne shall gain,
Of martial tow'rs the founder shall become,
The people Romans call, the city Rome." (Pg. 7)
As Aeneas makes his journey, lesser gods interfere with his passage. Juno who does not want Aeneas to reach Italy, tries to get him to stay in Carthage by having him fall in love with Queen Dido. To remain on course for his fate, Aeneas has the help of both Jupiter and Mercury, the later informs him of his destiny or fate and he leaves Dido, she then kills herself. Aeneas remains loyal to his fated destiny.
Further to the previous answer, the inevitability of the rise of Rome does indeed underscore the entire story of the Aeneid. However, whether intentionally or otherwise, Vergil brings out the cruel cost in human terms of this destiny's fulfilment. A number of characters, but principally Dido in the first half and Turnus in the second half of the epic, seem much more human and attractive as flesh-and-blood people than Aeneas himself and of course they are tragic figures in the classical tradition. It is one of the problems that Vergil set himself in telling the story: his 'hero' was going to appear to be simply an instrument of fate rather than a believable human being. The jury is still out on whether he successfully resolved this difficulty, but every time I read the bleak ending of Book 12 I am inclined to think that Vergil could see very well that the Roman power that he was apparently celebrating in the Aeneid also had a very dark and pitiless core.