The reason why Brutus and Caesar are not a true friendship is because Brutus even said in the beginning “What means this shouting? I do fear the people.Choose Caesar for their king,” (Shakespeare, p. 34). This
means that never has Brutus been a true friend or trust him since the beginning . Brutus always feared of Caesar of him becoming corrupt even when he never had true power or even close to being king , but just as a political alliance and that ended up with Brutus joing the conspirators and stabbing Caesar and them killing him.
Caesar would take a bullet for Brutus but it was clear Brutus wouldn't, and would instead shoot the bullet. This is why it was a political alliance and not a true friendship because Brutus didn't trust him with power because he always thought of him becoming corrupt and feared for the future of Rome as him as king and which led to Caesar's death.