|Physical appearance||Due to the metamorphorical nature of trolls, Brick looks like a brick wall|
|Parents||Adopted by Detritus and Ruby|
Brick is a troll born in Ankh-Morpork. Since trolls are made of metamorphorical rock, he has come to resemble nothing more than a brick wall (or, still being a troll, a brick outhouse, so to speak). Indeed, in Thud! reference is made to this fact. He witnessed the murder of Grag Hamcrusher, but, due to his propensity to utilize any available drug to fry his brain as frequently as possible, was not immediately aware of what he was seeing. It is believed that he found himself in the dwarf tunnels accidentally, while attempting to find a good place to enjoy his drug-induced hallucinations.
Before his patronage by Detritus, Brick was a loser's loser. Other trolls ignored and avoided him when possible, as real people ignore and avoid drug addicts and the homeless, and even those other lowlifes around him barely put up with him enough to let him scrounge Slab and not throw things at him. The most common sentiment he encountered was to be called a "sedimentary coprolite". He had next to zero self-esteem, himself vaguely aware that he had sunk so low that even the cockroaches spat on him.
Detritus drew attention to the fact that Brick is tougher and stronger than anyone has given him credit for. As well as surviving life on the streets as an unloved gutter troll, he can still be fairly rational, by troll standards, after much determined auto-frying of his brain on scrape: and most of all, he can still stand and fight, badly hurting Samuel Vimes himself, after taking a skinful of luglarr. These are qualities of underlying strength and resilience that a tough street-wise troll like Detritus may even admire in some way, and which influenced his decision to take a stern and loving paternal hand, or rather fist, in the upbringing of young Brick.
This metamorphorical rock business that has caused an Ankh-Morpork street troll like Brick to resemble nothing more than a brick wall is interesting. Brick (the building substance) is nothing more than fire-hardened clay. While other trolls may be snobbish about this, and look down on a troll who does not have the decency to take after a sought-after and socially approved material like granite or marble or other igneous rock, could it be that the quirk of troll genetics that defined Brick's physical form has absorbed (according to the elastic laws of Discworld genetics) something of the nature of the golem - a creature also made of fire-hardened clay? This may well explain the strength and resilience seen in this young troll.
Now that he's off Slab, the world is definitely looking better for Brick, as he is now capable of thinking to the end of sentences and still remembering the start of them, eating and not throwing it up, and it looks like he's going to follow Detritus and join the Watch, and maybe even make Lance-Constable. Mr. Shine, one of the few people who tried to help him, believed that Brick is pretty smart when he's not frying his brain, so who knows how far he could go?