Just before the conspirators attack Julius Caesar, Caesar is asked three times to lift the banishment of Publius Cimber. Knowing Caesar's arrogance and unrelenting will, Metellus Cimber, then Brutus, and then Cassius come forward to plead Publius' case, but they are really just getting close enough to surround Caesar before he is assassinated. Caesar's three refusals of mercy reflect back to the three times Antony offered him the crown and he reluctantly refused it. This demonstrates Caesar's strong desire to be the lone ruler and that his word is law. It is ironic that Caesar claims that he is "as constant as the Northern Star" moments before Casca makes the first strike.
Caesar seems very annoyed that these men are fawning all over him concerning this one request. to readmit Publius, whom he had banished, to Rome. I think he distrusts “These couchings and these lowly courtesies” displayed by these men who ask this of him. Caesar goes on to characterize the supplications of Metellus and the rest as “sweet words, / Low-crooked curtsies, and base spaniel fawning” (3.1 48-49). He asserts he banished Publius for a purpose (and we don’t know what that is), and will not reverse it based on such behavior of these men, which he seems to find embarrassing. While it is true he compares himself to a star to describe and valorize his constancy, we can also understand that as a leader he is trying to be fair rather than play favorites with his friends. Does he lack compassion? Probably. Does he act like a strong leader? Definitely. He says (paraphrasing this passage), “give me good reason and I’ll think about it, otherwise I won’t change my mind” (39-79).
He refuses to allow Metellus's brother, Publius, back into Rome. Publius Cimber had been previously banished and the conspirators used this petition to get close to Caesar.
His behavior is easy to describe: arrogant. Caesar metaphors himself to the Northern Star saying that as constant as the Northern Star stays in one place in the sky, so does Caesar stay with his decisions. Because he has already decided to banish Metellus, he will not consider allowing Publius to come back.