At Antony's house, Antony, Octavius, and Lepidus make a list of those who should be executed for their part in the conspiracy. Antony suggests they amend Caesar's will so it pays out less money, and sends Lepidus to get it. Antony then tells Octavius that Lepidus is too weak to share power, and should be gotten rid of once the struggle with Brutus and Cassius is over. They then discuss raising an army to meet the enemy.
This is a very different image of Antony from two scenes ago. Rather than Caesar's passionate friend, he is now a cold and sly politician. Octavius, by the way, is paying attention—he will eventually betray Antony and take sole power in Rome, as shown in Shakespeare's Antony and Cleopatra.