Gascoigne works in the courthouse as the justice's clerk. He is associated with the sign of Capricorn, and he is present at the Crown Council on the night the book opens. Gascoigne was a recent arrival to Hokitika, which means some of the characters meet him pretty much at the same time we do.
All in all, Gascoigne comes off as a pretty decent guy. In fact, apparently his number one fear was being selfish: "Selfishness was Gascoigne's deepest fear. He loathed all signs of it in himself …" (I.7.21). So, that seems pretty nice, right?
If you want a concrete example of Aubert's selfless and giving tendencies, just look at the way he helped Anna get out of jail. Despite the fact that they were strangers (and he was working for the people who had Anna locked up), Gascoigne fronted her the bail money—an act that the narrator assures us was pretty much par for the course with him:
This act of kindness, so unorthodox in George Shepard's gaol-house, was not a terribly unusual one for Gascoigne. It was his pleasure to strike up friendships within the servile classes, with children, with beggars, with animals, with plain women and forgotten men. His courtesies were always extended to those who did not expect courtesy … (I.7.18).
In other words, then, he tries to avoid being a snot, and in fact is attracted to people who aren't likely to be snotty, either.
So, in keeping with that general tendency, Gascoigne kind of avoids being too chummy with classier folks:
To the higher classes…he held himself apart. He was not ungracious, but his manner was jaded and wistful, even unimpressed … (I.7.18).
Ironically, though, that only drives those high-status people toward him, earning him "a great deal of respect" and "a place among the inheritors of land and fortune, quite as if he had set out to end up there" (I.7.18). Hmm, that works out well for him, now doesn't it?
Of course, Gascoigne's reluctance to get too chummy with uppity people might stem from the fact that he was born out of wedlock to an English governess and raised in humble circumstances…
Gascoigne was previously married to a woman named Agathe, but she died of consumption (i.e., TB). He seems to have a thing for Lydia Wells, until he realizes that she's marrying Carver. Luckily, though, he doesn't spill Anna's secrets to his crush—because probably would have probably been a disaster.
Which leads us to one final point about Aubert: he's smart—and he loves to read.