He is described as being probably around the ages of twelve to fourteen (he doesn't really know, having grown up on the streets with other things to worry about than birthdays).
Conn grew up in the Twilight, which is the shady part of the city of Wellmet. There, he learned to live off his own skills as a pickpocket and general thief. This lifestyle was brought to an abrupt halt on the day he picked the pocket of Nevery Flinglas, a wizard, and stole said wizard's locus magicalicus (magical focus). Simply by touching the stone, Conn ought to have died, but he didn't. This interested Nevery, who took Conn on as his servant, and later as his apprentice.
Connwaer had no schooling whatsoever, and could not read. Therefore he had to go to the academicos (school). Rowan became a temporary tutor, a daughter of the Duchess. He learns, and is put in a class with Keeston, Pettivox, which is assumed to be a traitor's apprentice. He later finds his locus magicalicus, a main part of the ducal regalia from the Duchess.
Conn's description on the Magic thief website is as follows:
He has shaggy black hair that hangs down over his eyes and bright blue eyes. He's been a gutterboy for most of his life, so he's watchful and a little wary; at the same time, he's completely pragmatic and truthful. He's thin, but he's sturdy and strong, too. He has a quirky smile (hence the cat's quirked tail). Conn does not know his own age; it could be anywhere from twelve to fourteen. A great friend to have, but be careful that you don't have anything valuable in your pockets in reach of his sticky fingers. He's a master pickpocket, a superb lock-picker, and a lover of biscuits and bacon.
He has messy longish black hair and bright blue eyes. He is small and skinny, but can hold his own in a fight.
He is curious by nature, eats like a pig, and is inarguably smart, even when he is academically lacking.
Conn is also seen to be protective of Wellmet's magic, and the magic has chosen him to protect. He understands most things about magic that even Nevery Flinglas could not understand (At first).