Isaac was raised to be Goblin Town's Master Builder. His father, the last Master Builder, was killed during the Accordance War in the Beltaine Night of Iron Knives massacre. For this, he holds something of a grudge against the Sidhe. In addition to his architectural mastery, he is an accomplished artisan and is responsible for many of the walking animal sculptures of the freehold. Having read Tapp's writings extensively, he is knowledgeable about all aspects of the freehold. He knows that something big is on the way and is prepared to do his best to protect Goblin Town.
As Master Builder, members of the freehold ask him everything. Cadmium has been asking, no... demanding... a map of the secret passage leading to Coma's chambers... again. He always tells her no, of course, and it's a good thing he's such a fast ducker. She doesn't seem to understand that being Master Builder is a sacred trust that he takes very seriously. The freehold is beautiful and he feels that if he weren't Master Builder there, he'd be nothing. He tries to share his enthusiasm for the place with anyone who'll listen. He knows there are some who would corrupt Goblin Town for political gain... he knows who they are and keeps an eye on them. Because his Seelie side can ride closer to the surface than that of most residents, he is somewhat unpopular in the community. He is highly sentimental as well.
Glass is a small man apparently in his very early twenties. He has lank, but well-groomed black hair, and is somewhat sickly looking. He has a tremor in his voice, perpetually shaky hands, and moves with a sort of nervous energy. He wears a thick pair of glasses and is always neatly dressed in a three-piece suit with highly polished shoes. His fae mien is the same, though his clothes are more archaic (late 19th century) and his glasses become a pince-nez. He is shorter than most nockers and his skin is pale yellow, not white or red, and his hands are always stained with ink from the feather quill pen he uses. He is usually accompanied by an unusually large, glassy-eyed nocker (really a chimerical golem) and a small jeweled dragon.
The description on Isaac in the book says he looks like he's in his early thirties. If he is a Wilder, this is hardly possible. The current editor has modified that part of his description to be more fitting with the ability and trait ratings given to him in the source book.