Francis Carver is the big bad in this novel, and all the nasty stuff that happens to the main characters can pretty much be traced back to him. In fact, he's even associated with some of the accidental bad stuff that happens. For example, when he's chatting with Anna one day, his horse gets startled and kicks her in the stomach (which causes her to lose her baby). Oh, and even though it was an accident, he's totally happy to take credit for having done it on purpose when that rumor starts going around. What a creep.
Unlike his girlfriend, Lydia, he doesn't seem to feel much remorse for his relentless drive to lie, cheat, and steal his way into a fortune—and a ship.
Francis Carver is associated with the planet Mars and the "related influence" of force. Mars is named after the Roman god of war, so it's no surprise Catton paired that planet with Carver, who seems to have zero problem using violence and order to get what he wants.
Ben Löwenthal pegs Frank's key characteristics pretty dead-on early in the novel:
I suppose that my impression of him is not altogether a good one. He is a rich man's son first and a convict second, but it might just as well be the other way about: I believe he shows the worst of both worlds. He's a thug, but he's conniving. Or, to put it another way, his life is lavish, but it's base. (I.6.256)
So, yeah, he has a taste for the finer things and money, but his behavior is anything but classy …
Since Sook fell victim to Carver's swindling powers early in his life and knew him for several years, Sook's backstory gives us some insight into what Carver was like back in the day:
Carver was a terse and brooding young man, born in Hong Kong to a British merchant trader, and raised at sea. He was fluent in Cantonese, though he cherished no love for China, and meant to leave that place as soon as he acquired a ship of his own—an ambition he referenced very frequently. (II.8.102)
Sure enough, as soon as Carver's daddy bought him a ship, he started making runs away from China…and, it turns out, running opium using Sook's family name and warehouse as a cover. As a result, Sook's father ended up getting executed without trial. So, yeah, remember when we said Carver was pretty evil? He is.
To make matters worse, Sook didn't initially realize Carver was involved in what happened to his dad, so he stayed friends with him—and begged to follow him to Sydney. Carver reluctantly agreed, but then he immediately left Sook to his own devices upon arrival and refused to help when Sook got into trouble. At around that time, Sook got wise to Carver's involvement in his dad's execution and resolved to kill his old buddy. What can we say—what goes around comes around.
Of course, soon after that, Carver's illegal activities came to light, his ship got seized, and he was sent to prison for ten years (under George Shepard's watch). As a result, when he got out, he was once again a man without a ship…and therefore even more hungry (for a vessel) and greedy than he was before. This probably explains why he was so eager to dupe Alistair Lauderback out of the Godspeed.
Another key fact to know about Carver is that he has a big, ugly scar on his face courtesy of Crosbie Wells. Although we don't learn it right away, it seems that Crosbie gave it to him when trying to carve a "C" into his face, as retribution for going around using Crosbie's name. The end result was anything but beautiful:
The white scar on his cheek was slightly puckered at one end, as when a seamstress leaves the needle in the fabric, before she quits for the day; this phantom needle lay just beyond the edge of his mouth, and seemed to tug it upward, as if trying to coax his stern expression—unsuccessfully—into a smile. (II.8.7)
Hmm, Frank is actually pretty stern, so you probably would have to pull his mouth to make that happen.
Unfortunately, Carver seems to get the last laugh on Crosbie. We don't know exactly what happens, but Carver visits him on the evening of January 14th, and soon thereafter Crosbie is found dead. The narrative never spells it out explicitly, but we have every reason to believe that Carver added Wells to his body count that night.
Carver's own death is also a point of ambiguity in the book, since we don't actually "see" what happens. You see, he had been arrested at Anna and Emery's trial, and was in the process of being taken back to prison when someone broke into the carriage and bashed his head in (while Drake, the driver, rode merrily on, unaware). Again, the narrative never spells it out, but we get lots of clues that Te Rau decided to avenge Crosbie's murder by killing Carver.