The more serious answer: :p
Brutus was Servilia's son, and heir of the gold of Tolosa, if you believe the story about Servilia's father, Servilius Caepio. I happen to believe that story, which would in fact make Brutus richer than Crassus.
Colleen McCullough puts Brutus in love with Julia (the one who died at the beginning of the Rome series, Pompeius's wife), and heartbroken that Caesar married her off to him instead... and more devestated that it was a love match.
That is just as likely to be right as it is wrong, but what's also true is that Cato is Servilia's half-brother, whom she of course despises, her a patrician Servilius, and him descended from a celtiberian slave. Cato is more or less the mouthpeice of the poltical faction known as the boni, ultra-conservative, and oppossed to all things Caesar. Cato bullies Pompeius into war, as I think that's shown in the series as well. Keep in mind that this Cato would have been younger, fresh into the senate in his mid-thirties.
I think it's just as likely that Cato got to Brutus. After all, it was a Brutus who killed the last king of Rome. Whether or not Caesar gave him a shove by taking away his girlfriend, who knows?
Yup, these real stories have everything, no need to change them around like they do on tv.
As for looks, the two closest in looks on the show would be Pompeius and Cicero...even if the timeframes are wrong. Cicero did have those huge ears, and Pompeius was a bit out of shape by this time as well. Caesar by all accounts had blond hair and blue eyes, and a properly Roman nose. His hair would also have been receding at this point, which he used the civic crown he won in battle to cover the receding hairline. Why? The irony of having a cognomen that means "a fine head of hair."
Cato had reddish hair and a huge honking nose, so yeah, Cato and Caesar don't match at all.
It's all in the history books, just waiting for their consultant to actually read. :p
And where is Bibulus?? I only watched the first two episodes before turning away in disgust. Please tell me that Bibulus appears sometime?