Note to JULIUS CAESAR, 5.1.20, 'I do not cross you; but I will do so'
Here are two different ways of interpreting this line:
1) Octavius denies that he has contradicted Antony (though he has) and insists that he will do as he has said he would: go right, instead of left, as Antony told him to.
2) Octavius gives in to Antony and says that he will not cross him (move from left to right) now, but predicts that he will cross (oppose) him in the future.
In either case, Octavius, the future emperor of Rome, is displaying the force of his will. Also, this conflict between the two is more dramatic when you know (as many in Shakespeare's audience did) that at the time of Caesar's death Antony was 39 years old and an experienced military man, while Octavius was 18 years old and in military training.