How does Julius Caesar's death negatively affect Brutus, Cassius, and Antony?
Brutus: Although Brutus felt that Caesar needed to die to save the Republic, Brutus had been very close to Caesar and was grieved by his death. Also, after Caesar’s death, Octavian (to become the Emperor Augustus) and Marc Antony turn the crowd against Brutus and the other conspirators, plunging Rome into civil war.
Cassius: As the other conspirators, he is proscribed and condemned by Antony and Octavian.
Marc Antony: Marc Antony feels that Rome will be worse off having been deprived of such a great leader. Personally though, he benefits from Caesar`s death both practically (he is favoured by Octavian) and in terms of character – he seems to mature and become less of a soldier/playboy and more of a statesman as he rises to the occasion (although Shakespeare`s Antony and Cleopatra shows him reverting to type.)