Antony is not actually present at the site of the assassination because one of the conspirators deliberately detains him outside by engaging him in a prolonged conversation. Antony prudently flees to his home when Caesar is killed. He realizes that his own life is in extreme danger because he was such a close friend of Caesar's; and furthermore he has no way of knowing how many other men the conspirators intend to slaughter. It is probably only because Brutus is such a moderate and kind-hearted man that the conspirators do not conduct a general slaughter of all Caesar's friends and supporters. This is what Antony and Octavius will do later when they have seized power.
Antony sends a servant to Brutus to find out whether it would be safe for him to put in an appearance. After all, he knows there is no point in his staying at home. If they want to kill him they can easily find him. When he appears in Act 3, Scene 1, he acts extremely meek and humble. Characteristically, Brutus tries to explain his reasons for leading the attack upon Caesar, just as Brutus will try to explain his reasons to the mob attending the funeral. Brutus thinks that men are motivated by reason, whereas both Antony and Cassius know that men are motivated by emotion and self-interest.
The most significant words spoken by Antony during this meeting are the following:
I doubt not of your wisdom.
Let each man render me his bloody hand:
First, Marcus Brutus, will I shake with you;
Next, Caius Cassius, do I take your hand;
Now, Decius Brutus, yours: now yours, Metellus;
Yours, Cinna; and, my valiant Casca, yours;
Though last, not last in love, yours, good Trebonius.
Gentlemen all,--alas, what shall I say?
My credit now stands on such slippery ground,
That one of two bad ways you must conceit me,
Either a coward or a flatterer.
That I did love thee, Caesar, O, 'tis true:
If then thy spirit look upon us now,
Shall it not grieve thee dearer than thy death,
To see thy thy Anthony making his peace,
Shaking the bloody fingers of thy foes,
Most noble! in the presence of thy corse?
Had I as many eyes as thou hast wounds,
Weeping as fast as they stream forth thy blood,
It would become me better than to close
In terms of friendship with thine enemies.
Pardon me, Julius! Here wast thou bay'd, brave hart;
Here didst thou fall; and here thy hunters stand,
Sign'd in thy spoil, and crimson'd in thy lethe.
O world, thou wast the forest to this hart;
And this, indeed, O world, the heart of thee.
How like a deer, strucken by many princes,
Dost thou here lie!
Antony not only wants to save his own life, but he wants to get permission to speak at Caesar's funeral. He secretly intends to stir up the citizens against the conspirators. The audience should be well aware that Antony is lying, flattering, and pretending in a perilous situation. Cassius does not trust him at all. He has wanted to kill him ever since the conspirators met at Brutus's home, and it is only because of Brutus's trusting nature that Antony manages to stay alive. Cassius characteristically responds to the speech quoted above by telling Antony:
I blame you not for praising Caesar so;
But what compact mean you to have with us?
Will you be prick'd in number of our friends;
Or shall we on, and not depend on you?
Cassius, the realist, is right about Antony. Brutus, the idealist, is wrong.