Shakespeare evokes sympathy for Brutus by showing just how troubled he feels over the conspiracy against Caesar. He does go along with it, but his inner turmoil comes to the fore in a soliloquy:
Since Cassius first did whet me against Caesar,
I have not slept.
Between the acting of a dreadful thing
And the first motion, all the interim is
Like a phantasma, or a hideous dream:
The Genius and the mortal instruments
Are then in council; and the state of man,
Like to a little kingdom, suffers then
The nature of an insurrection. (II.i.61-69)
Brutus is thus ‘with himself at war’, as he declared earlier to Cassius (I.ii.46). Portia, Brutus’s wife, also remarks on how distraught he has been lately. He is grateful for her concern, although he feels unable to confide in her. We are therefore given both an internal and external picture of Brutus as a man who is deeply troubled.
Brutus is conflicted over the killing of a personal friend, but in the end he agrees to it because of his political persuasion that Caesar must be sacrificed for the ultimate good of the state: he cannot be allowed to become too powerful. At the same time, Brutus is determined not to let things get out of hand, for instance he rejects Cassius’s proposal that Antony, Caesar’s close supporter, should also be killed. This decision turns out to be a political mistake, as Antony will go on to turn the people of Rome against the conspirators, but it stems from Brutus’ own nobility; he will kill Caesar as he deems it a political necessity, but he will not kill anyone else. He is not motivated by bloodlust.
Brutus’s nobility is stressed throughout the play; even Antony pays him tribute at the end. We feel for Brutus as a man who is compelled to act against his better nature, and who is then unable to control the consequences of his own fateful actions.