Brutus establishes his credibility by asserting authority when he tells the Romans to remain quiet so as to be able to listen to his speech.

He also asks the plebians to believe him for he is honourable and an honoured man is not one who can lie. Thus the people should trust him. manipulating the audience to believe him and his antics

Through the use of the word 'love', he creates a bond between him and the deceased Caesar, which furthers his credibility as he resonates as a beloved friend and not as an enemy

Brutus begins to speak in 3rd person, this highlights how his love for Caesar is almost out of body and that even if he wasnt Brutus he would still love him all the same

furthermore, he garners support of the plebians by establishing that his love for caesar was the same as theirs and that the murder of caesar was not personal but rather for the good of Rome.

Through the asking of a series of questions he includes the Romans into the conversation making them feel like he is one of them, that he 'Brutus' is also Roman as well as that if they were in the same position they would have killed Caesar too.

With this Brutal statement, he tries to use reason to showcase to the plebians why he killed Caesar. It was a neccessity in his pereiphery and he wanted to show the romans why it had to be done.