Tanner Mirabel was a former soldier/assassin from Sky's Edge, later becoming security chief to arms trader Cahuella. A ruthlessly efficient and intelligent fighter, he fails to prevent an ambush, and accidentally causes the death of Cahuella's wife. His mind is subsequently trawled by Cahuella, his memories and identity used to create a disguise, allowing Cahuella to leave system seeking revenge, while Tanner is left for dead as punishment for his failures.
Most of our knowledge of Tanner comes from the stolen memories Cahuella implanted into himself, however these are increasingly tainted by the morality and character of Cahuella himself, making reliable character description difficult. When Tanner does, for a short while, appear in Chasm City, he seems considerably colder and more amoral than the version we see through the minds-eye of Cahuella. (Although it is implied that this is because of Cahuella's torture of him by feeding him to a hamadryad, an alien monster native to Sky's Edge). Tanner expertly kills Reivich near the end of Chasm City by throwing a knife into his head, a brief scuffle with Sky Haussmann ensues where Tanner is easily the stronger and more powerful antagonist. Tanner would have killed Sky, had he not been bitten in the neck by special fangs and venom glands implanted in Sky's mouth during his years under the identity of Cahuella.