Quibble was a Neoteric who joined the anti-Sanctuary. She refused to kill the baby of some innocent bystanders during the capture of Temper Fray; offering instead to wait 18 years and kill the adult then. Because of this lack of cooperation, she is killed by Lethe. After her death, Memphis reveals that Quibble was his sister, but he doesn't seem too fussed and doesn't hold it against Lethe.
As shown by her unwillingness to kill a baby (because it was "annoying" Lethe), she had a soft spot somewhere. Even though she joined the anti-Sanctuary, indicating that she despised and wanted to rule over the mortals, she had principles about killing people. Lethe finds this sad.
When confronted with a seemingly inescapable scenario, Quibble is described by Temper Fray to be an "Option Three kind of girl", where Option Three is not to run or to beg, but to fight her way out. As soon as she realises she is going to be killed, she aims her gun at Lethe.
Quibble was bald.