Cyriana au Tanus, better known by her nickname Thistle, was a Bonerider serving under The Jackal. She was a fellow housemate and ally of Darrow in The Institute, as well as a former Howler under Sevro. Like Roque au Fabii, Thistle began to doubt Darrow's leadership as a fleet commander when he made strategic mistakes that caused the deaths of many of her friends. She, along with Roque, defected to The Society's side during Darrow's Triumph and downfall.

Thistle subsequently entered The Jackal's service as a Bonerider. She was captured and imprisoned along with Antonia au Severus–Julii during the Battle of the Jovian moons. She expressed guilt at the sight of her captors and former friends, and pleaded to reveal strategic information about The Society in exchange for freedom, but was murdered by Antonia before being able to do so. Sevro and the other Howlers were saddened by her death.