These qualities in Brutus make him the one or one of the most honorable man in Rome, but they also make him a difficult man to trust, as his loyalty is to Rome herself. He may seem trustworthy on the surface, but after you understand his motivations, Brutus is a very complex person as he owes his allegiance to Rome alone.
Caesar trusted Brutus and admired his strong sense of honor so he pardoned him. Previously, Brutus sided with Pompey’s, Caesar’s enemy, faction. Rightfully, he, along with some others should have been executed. In turn, Brutus looks up to Caesar as his role model.
Yet, Brutus backstabbed him, literally. Even Caesar is disbelieving that someone he loves and respect would actually do such a thing to him. Caesar's dying words are, "Et tu, Brute?" (You too, Brutus?)
This is the best example to show that Brutus is not to be trusted. After all, Brutus reasoned “Not that I loved Caesar less, but I loved Rome more.” This shows that Brutus will not hesitate to remove anyone who he thinks is a threat to Rome’s democracy, or maybe more accurately, a threat to his own set of values.
Continuing that, although it is Cassius who first approaches Brutus and tries to persuade him to join their cause, he has previously already given some thought to the notion of killing Caesar. He says to Cassius, “What you would work me to, I have some aim. How I have thought of this and of these times, I shall recount hereafter.” These lines show that before Cassius even talked to Brutus about removing Caesar, he had already come to that conclusion by himself. Most people tend to think that it was Cassius’s words that made Brutus