How does Antony respond to the conspirators immediately after Caesar's murder? Why does he behave this way ?

Antony arrives and laments the death of Caesar, begging the murderers, specifically Brutus, to explain why Caesar had to be killed. Brutus tells him that Caesar was destroying the republic and had to be removed from power. Antony pretends to be convinced by this and asks the conspirators to, "Let each man render me his bloody hand" (3.1.185). He then shakes hands with each of them, naming them as he faces each man. The last hand he takes is that of Trebonius, who actually did not commit the murder, but distracted Mark Antony so he would not be able to protect Caesar.

Mark Antony does not believe the conspirators are justified in crying "peace", and is the first to condemn their actions. When Antony states, "Let each man render me his bloody hand" (3.1.185), he is marking them for revenge rather than celebrating their actions. Even Trebonius, who did not stab Caesar, but prevented Antony from protecting him, is marked by Antony. Antony shakes hands with Trebonius last, transferring Caesar's blood, collected from his previous handshakes, to his clean hands.