A Letter from the Past, Part 2 (Chapter)

The Vow to the Father (A Letter from the Past - Part 2 in the JoJonium release) is the seventh chapter of the JoJo's Bizarre Adventure manga. It is also the seventh chapter of Part I: Phantom Blood.

Summary
There is a flashback to seven years earlier, where Dio is seen trying to give his father some medicine, only to be struck by Dario, who would rather drink alcohol than take medicine. Dario throws his deceased wife's dress to Dio; he tells him to sell it for alcohol saying he does not need the clothes of some dead woman. In reaction to this, Dio cries and resolves to kill his father, and is seen afterward buying oriental poison from a man in London. Though Dio is wearing a mask at the time, the man selling the poison takes note of the three moles on his left earlobe before giving him the final dose.

Back in the present, Jonathan has realized that Dio killed his own father, Dario, and is trying to use the same poison to kill George. When he is confronted about this, Dio denies this claim, but Jonathan says that he plans to investigate the medicine Dio has been delivering to George to see if it is legitimate. Jonathan snatches the paper package off of Dio's tray and refuses to give it back. As Dio tries to retrieve the "medicine" he threatens Jonathan saying that their friendship would end if he did not trust him him and return it. Jonathan is unable to meet Dio's eyes because he knows that his claims are based entirely off of his own feelings and have no solid proof. In response he asks that Dio swears his innocence on his father's honor, saying that he will return the medicine and never speak of it again if he does. As Jonathan had expected Dio refuses, saying that someone like Dario had no honor at all. The thought of Dario enrages Dio, and he punches Jonathan; however, years have passed and Jonathan is much stronger now. Jonathan has resolved to protect his family, so he grabs Dio and throws him down through the railing from the second story of the house to the first.

Jonathan knows that he and Dio were never really friends, and says that he will make sure to get the medicine analyzed and send Dio to jail. Dio knows it will take Jonathan at least three days to find proof of the poison, due to it being from the east, and determines finish off Jonathan before then.