Doctor Theophrastus ‘Theo’ Campbell is a linguist from the Core world of Britannia. He's considered brilliant, by those who haven't met him, with a knowledge of many of the nearly extinct old Earth languages of far-flung humanity. Theo is the twin brother of Ari, from the first book in this series, Restricted, but while the two may be identical in appearance, their personalities are an entire universe apart. Where Ari was very introverted, Theo is extremely extroverted and hyperactive, seemingly incapable of being quiet or still for very long.
Doctor Aristotle ‘Ari’ Campbell is a scientist from the Core world of Britannia. As such, he's more used to the ivory towers of academia than the rough and tumble worlds on the Verge, where a barrier supposedly keeps out the ruffians of restricted space. He's only there because he's desperate to find his kidnapped twin brother Theo. To help him navigate the Verge and the restricted space beyond, Ari enlists the aid of Orin, a down on his luck pilot in desperate need of work and a ship.