Sophocles' Antigone opens with an encounter between Antigone and her sister Ismene. They are discussing the recent death of their brothers, Eteocles and Polyneices, who fought against each other and died in a war that later came to be known as "The Seven against Thebes." Eteocles fought in defense of Thebes, whereas Polyneices fought to regain the kingship of his native town.
Antigone tells Ismene about King Creon's decree that anyone who buries Polyneices "will be stoned to death before the city" (Ian Johnston's translation). Despite this decree, Antigone indicates that she will "take up Polyneices’ corpse and bury it."
Thus, I don't really think "foreshadowing" is the right word to describe what the playwright here in the prologue. It seems quite clear that Antigone intends to bury Polyneices and, given Creon's decree, we would be quite surprised if she were not killed as a result of violating that decree.
Antigone's suggestion that if she is put to death that "I’ll lie there with him" is interesting, because the "him" might be ironic foreshadowing of the death of Haemon, her fiance, who will die in the underground enclosure with Antigone.
As for Antigone's character, it is clear from the outset of the play that she is defiant in the face of human law and that she will be loyal to her loved ones, even though the city has declared them outlaws.