Caha was one of Cesare Borgia's agents and assassins the Roman underworld, who killed her targets dressed in a colorful jester costume alongside her brother Cahin.
Little is known of Caha's background save that she was a corrupt French noble who came to Cesare Borgia and the Templar Order's attention. She and Cahin would perform murders in the Borgia's name dressed in colorful jester costumes. During one mission, Cahin and Caha worked with Cesare's top agent Fiora Cavazza, who was intially annoyed by the pair before warming up to them following their killing a large number of targets together. However, when Fiora Cavazza left the Templars and became an "ally" to the Assassins, she sold the two jesters out to the Assassins. Recognizing Fiora, Caha attacked her, but after her brother Cahin was killed broke down in despair. As she cradled her brother's body she was killed by another Assassin with a crossbow bolt.
In 2012 her genetic memories were used to construct an Animi Avatar in her likeness dubbed "The Hellequin".
Cahin and Caha translates to "Wily Nily" in French.
The Hellequin is a real historical type of jester that in fact predates the Harlequin. Both are typically considered "The Devil's Jesters" and the Hellequin features in Dante's Inferno.