Because she certainly does that. In First Man in Rome, Servilia is just a baby, so she has no chance to make her personality felt. The only significant thing about her is that her mother (Livia Drusa) doesn't love her because she hates her father, and her father (Quintus Servilius Caepio) doesn't love her because he wants a boy.
But at the age of seven, she already establishes herself as evil in The Grass Crown. She is a patrician Servilian whose grandfather was a tremendous snob as a matter of historical record, so it is not so far-fetched to suspect that he passed the attitude on to his son, who passed it on to his daughter. But it is still possible to be snobby and still be decent in other ways. Servilia is not. Unloved and unwanted by either parent, she nonetheless sides with her father. By the age of seven, she knows how to be hurtful. ("We only talk about important things," Servilia tells her mother. "We don't talk about you.") While her father is away on a long business trip, Servilia's mother moves them out into the country and pretends to go on long walks, but actually carries on an affair with Cato Salonianus and gets pregnant so soon that she is able to pass her son off as legitimate. Servilia makes an off-hand remark about her mother having a "friend," and her mother looks so panicked at the mention that Servilia follows her on one of her "walks" and finds out what is really going on.
QSC comes home and is so angered at his wife's coldness toward him that he starts beating her and then discovers that he is really a sadist. Livia's brother, Marcus Livius Drusus, the non-protagonist hero comes to her rescue (and makes up for forcing her to marry him in the first book). The Servilia steps forward with the Big Reveal of her mother's affair and says, "Don't just beat her. Kill her! She deserves it." QSC walks out and divorces his wife. Although under Roman custom, when a couple divorces, the children go to their father, but QSC refuses to accept any of them, saying that he does not believe any of them are really his. Drusus therefore takes responsibility for the children. Livia marries Cato Salonianus, and the couple stay with Drusus, who is married to QSC's sister.
Drusus is the biggest champion of Italian citizenship, which Servilia and her father snobbishly reject. Despite her father's rejection of her, Servilia acts as his spy, sneaking through the papers of her uncle's guests and letting her father know what they are up to. When Drusus finds out, he confines her to the house and will not even let her leave the nursery without being watched. Knowing Servilia's snobbishness and what will hurt her most, Drusus threatens to marry her to a country squire with no pedigree. Servilia curses the four adults. "May you all be dead before I 'm old enough to marry."
And, of course, under the rules of fiction, these curses always come true. Drusus' wife is pregnant and perfectly well, but shortly afterward she develops a hemorrhage and dies. When Servilia is ten, her youngest brother is born in the breach and her mother is damaged in the birth. She seems to be making a good recovery until Servilia says, "You will die because I wish you dead. I have the evil eye." She claims that her aunt is dead because she wished her dead. Well, as we all know, these curses can work if you believe in them. Servilia's mother worsens and dies. Cato Salonianus, broken-hearted, takes a foreign assignment and is killed. Three down, one to go! The nursery is the scene of endless fights and quarrels between the half-siblings, driven mostly by Servilia and little Cato, with Servilia taunting the Cato children for their inferior pedigree. And then Drusus, on the verge of admitting the Italians to citizenship, is fatally stabbed and dies, screaming in pain. The other children huddle together in the nursery, crying, but Servilia comes out to investigate. Sulla asks her what she is doing and she says she is looking for her father. Sulla tells her her father wouldn't dare show is face because people suspect him of being behind the murder. Servilia's face lights up. "Is he really dying?" Sulla tells her yes. "Good!" That is the last we see of her in The Grass Crown.
In Fortune's Favorites, the author allows us maybe a glimpse of sympathy for Servilia, spending her childhood imprisoned in a house where she is unloved and unwanted. She is given in marriage to Marcus Junius Brutus, who lets her come and go as she pleases, but neither loves nor wants her. He carries on his life as if she weren't there at all, never invites her anywhere or shows her anything he buys, never lets her into his study, sends her away when he has friends over, and sleeps in a separate room. He is dominant and she never dares displease him lest he divorce her and send her back to her uncle's house. Their relationship does not go much beyond his occasionally going to her for sex, a tiresome business for Servilia, but one she is glad he did anyhow because it results in a son. So she puts all her love-starved energy and loneliness, hopes, dreams and longings into this one baby. Poor him!
She also reminds us that, despite this flash of sympathy, she is still evil. When the laundry girl holds the baby, Servilia gets jealous and hits her so hard that she drops him. Servilia then says to flog and sell her, but the beating is so severe as to make the girl worthless, so Servilia has her crucified, leading at least one reviewer to hope that she dies in a fire.
She doesn't kick all that many dogs for the rest of the novel (at least not compared with the last one). When Sulla starts drawing up hit lists of his enemies, Brutus is not on it, even though his father and uncle were killed fighting against Sulla. He realizes that is because his wife is the niece of Sulla's son-in-law. Suddenly, he does not dare divorce Servilia and the balance of power in their marriage begins to shift. He discusses worldly matters with her as an equal. Servilia begins to take a most unfeminine interest in politics and to cultivate her information network among the wives of the elite, subtly drawing them out on what their husbands are up to and turning out to know a lot more than her husband. And then she starts thinking her husband is not important enough to be worth talking to and conveys the information to his superior. She becomes more and more the dominant partner, treating her husband almost as disdainfully as he once treated her. He ends up leading a rebellion and being killed in a futile attempt to impress her. Some of her more conservative relatives disapprove when she resolves to remarry as soon as she can. This gives her a chance to show how much she despises her relatives, especially Cato. The last we hear from her is from Caesar's mother who says she has remarried and had two daughters and who comments on her political savvy. Caesar is uninterested. He will become very interested indeed in the next book.
So, in the end, the question has to be, McCullough could portray Servilia any way she wanted. Why does she decide to make her so evil? I can think of several possibilities.
- Servilia defies the accepted Roman role for women. She is assertive, meddles in politics, and swears like a man. In the next book, she will have an extended affair with Caesar. Maybe the author has adopted Roman prejudice against women who don't know their place. On the other hand Caesar's mother also defies conventional Roman roles for women (at least upper class Roman women). The author never thinks less of her.
- Servilia's grandfather was a truly odious man. Maybe the author thinks the apple never falls far from the tree.
- Servilia is the mother of Brutus. Maybe the author couldn't forgive her for that.
- And finally, there is a general consensus that the author is in love with Caesar herself. Maybe she resents Servilia as a romantic rival.
Make of it what you will.