恺撒为马库斯·朱尼乌斯·布鲁图斯（也被称为昆图斯·塞维利乌斯·卡皮奥·布鲁图斯）出谋划策，在法萨卢斯与恺撒及其对手庞培站在一起后，他放过了布鲁图斯，然后选择他为44岁的总督。在莎士比亚的《尤利乌斯·凯撒》中，凯撒只有在看到布鲁特斯也反对他的时候才下定决心去死。对这种偏爱行为的一种解释是，恺撒可能是布鲁特斯的父亲。

凯撒与布鲁图斯的母亲塞维利亚（Servilia）有着激情而长期的恋情，塞维利亚是卡托的同父异母妹妹，保守派参议员，也是凯撒的死敌。西塞罗在给朋友阿提库斯的一封信中称她为“热情的朋友，也许是凯撒的情妇”。布鲁特斯为他的反君主家族遗产感到自豪，他是著名的朱尼乌斯·布鲁特斯（Junius Brutus）的后裔，帮助赶走了罗马国王。但塞维利亚也有这样的祖先；正如普鲁塔克在其《布鲁图斯的一生》中所述，“布鲁图斯的母亲塞维莉亚的血统可追溯到塞维利乌斯·亚哈拉”，她杀死了“煽动性地阴谋篡夺绝对权力的斯普鲁乌斯·马利乌斯”

​有一次，当凯撒和卡托在参议院遭遇击倒时，他们展开了一场旷日持久的战斗。根据普鲁塔克对卡托的描述，“有人从外面给凯撒带来了一张小纸条。”。​卡托认为凯撒卷入了某种阴谋，并要求把纸条大声读出来；让事情变得非常尴尬的是，这张纸上竟然有塞维利亚写给凯撒的情书！卡托把信扔给凯撒，继续说着。

布鲁图斯是凯撒的儿子吗？

凯撒在与塞维利亚的婚外情中会生下一个儿子吗？可能地有人反对凯撒在布鲁特斯出生时只有15岁，尽管这几乎不排除这种可能性。如果恺撒是他的父亲，那么布鲁特斯将成为比现在更糟糕的罪犯，因为他犯下了弑父罪，这是最可怕的罪行之一。尽管如此，大多数学者还是不相信凯撒是布鲁特斯的父亲。

普鲁塔克在公元110年左右的著作中并没有明确地解决这个问题，但他确实解释了为什么凯撒可能认为布鲁图斯是他的儿子。普鲁塔克《布鲁图斯的一生》中关于父亲身份问题的第五段，包含了一个相关的、著名的轶事，同时展示了凯撒击败布鲁图斯的叔叔卡托，以及凯撒与布鲁图斯母亲的关系是多么持久。

And this he is believed to have done out of a tenderness to Servilia, the mother of Brutus; for Caesar had, it seems, in his youth been very intimate with her, and she passionately in love with him; and, considering that Brutus was born about that time in which their loves were at the highest, Caesar had a belief that he was his own child. The story is told, that when the great question of the conspiracy of Catiline, which had like to have been the destruction of the commonwealth, was debated in the senate, Cato and Caesar were both standing up, contending together on the decision to be come to; at which time a little note was delivered to Caesar from without, which he took and read silently to himself. Upon this, Cato cried out aloud, and accused Caesar of holding correspondence with and receiving letters from the enemies of the commonwealth; and when many other senators exclaimed against it, Caesar delivered the note as he had received it to Cato, who reading it found it to be a love-letter from his own sister Servilia, and threw it back again to Caesar with the words, "Keep it, you drunkard," and returned to the subject of the debate. So public and notorious was Servilia's love to Caesar.

-卡莉·西尔弗编辑