Isaac's home city is a steam/dungeonpunk Fantasy Counterpart Culture of Victorian London, with all the grime and nastiness that entails. This makes him generally distrustful of authorities (the New Crobuzon Militia are a fascistic combination of military and secret police). He's also used to scarcity, even in his relatively comfortable scientist-for-hire borrough, and will often assume of others on the engineering team that they are competing with him when they aren't.

He isn't actually "Black" in the way we would parse culture as that cultural division does not exist on Bas Lag. The oppressed minorities there are Xenians (non-humans). Being involved in an extended affair with a Xenian woman and a subscriber to the illegal newspaper Runagate Rampant, he is easily sympathetic to those fighting for their rights and will take their side.

Most of his friends are bohemians of some stripe, which means he's definitely a party dude and can appreciate good art.