Flavius and his friends walk the streets of Rome and say "go good countrymen and for this fault assemble all the poor men of your sort" (l:i:Ln57-58). They dont like Caesar taking power in rome.
Act iv sc iii
i am the ghost of Caesar "To tell thee thou shalt see me at philipi"(iv:iii:Ln290)
Brutus And the other guys get him to be part of the plan. They are all over at Brutus's house talking about what to do. They all figure it out and go home to get ready for the plan. " rome i make thee promise if the redress will follow \, thou shal receivest" (ii:i:Ln56)
Act V: Sc V
The guys followed Cesar to the government building and went along with their plan. They all stabbed Caesar after he did not let one of their brothers back into Rome. Caesar was hurt when he saw Brutus Stab him. He thought he was his friend Caesar said "Et Tu, Brute? Then fall, Caesar."(iii:i:Ln 77)
When Brutus and Antony get done arguing Brutus goes to bed.He said he wants to leave first thing in the morning. Then the ghost of caesar shows up then he changes his mind and wants to leave then.
This is when brutus killed himself. He did this because all of his friends have been killed. He blamed it on Caesar's ghost. He also wanted to die Because he thought it was the best for rome he said "Caesar, now be still; I killed not thee with half so good a will"(V:V:Ln50-51)
The lesson i learned from this is you cant trust everyone. Just because people say they are your friend it can always come back and haunt you. I learned that you should follow what you think not others.