A World of Darkness : Austin
Not much is known about Martin, other than he seems to have control over the Arcanums of Death and Prime at least.
Martin helped Michael Colvin after his awakening, taking him and showing him the ropes and eventually introducing him to the Mysterium. Along with Michael he works at the Texas Archaelogical Research Laboratory (TARL) at the JJ Pickle Research Center.
In Party at the Monarch he was found to be responsible for a plan to murder hundreds of people, and destroy the monarch building. He also had used runes that seem to be Atlantean, only… not. They hurt the eye to look at, and seem somehow wrong to anyone who knows the Atlantean language.
In Visit to a Carnival, he was released after agreeing to a pledge against mass murder or hurting any of the group that stopped him. As part of the pledge he had his grimoire returned to him, though his laptop was pawned.