How does Julius Caesar connect, extend, and/or challenge the perspectives offered on fortune and luck in The Prince?

The action of Julius Caesar can definitely be seen as connected to the principles stated by Machiavelli not only in chapter 25 of The Prince, but also elsewhere in the book. Machiavelli indicates that a leader has to understand the spirit of the times and the direction in which events will move based upon it. The defeat of the conspirators against Caesar is at least partly due to misunderstanding of the feelings of the Roman population—they do not have their finger on the pulse of the population. Brutus and the others are clueless about Caesar's genuine popularity with the "plebs," as well as the devotion Antony can elicit. Unlike Antony, Brutus and the others have no grasp of mass psychology. They are caught off guard by the riot that begins after Antony's oration. The crowd's response is like the uncontrolled torrent of a river, which Machiavelli likens to fortune. In contrast to what Machiavelli recommends, the conspirators have no idea of how to react to this force. Brutus, despite his ideals, lacks the virtù (which, in Machiavelli's usage, means "strength" as well "virtue") needed for leadership.
The other central point about Brutus in particular is that he is actually (as Antony states ironically) "an honorable man." In chapter 18 of The Prince, Machiavelli discusses when it is expedient for a leader not to be honest. He is not so much advocating for lying as much as describing the actions of princes that have made them successful. Alexander VI, he says, hardly ever took any kind of action without being deceptive. Brutus and the other conspirators, even Cassius, are too honest. In their idealistic way they extol "liberty, freedom, and enfranchisement," but seem unaware that the people are not motivated by this. Instead, they are motivated by a visceral loyalty to Caesar and their emotional connection to him. Through history we have seen this scenario acted out again and again, including in our own time. A leader can be valued on an irrational level by people because they like the way he talks, even if the things he says make no sense. Brutus makes sense in his speech to the crowd—and they seem to recognize this at first—but ultimately, his appeal to the intellect falls on deaf ears.