After the creation and failure of the vert first Matrix, The Architect created a second, more nightmarish Matrix based on the atrocities found throughout human history. Within this "nightmare" Matrix, The Architect created supernatural monsters to fit the environment of suffering intended for its human residents.
Amongst the myriad of monsters from this early version of the Matrix were werewolves, like Abel, vampires, like Cain, and phantoms, like The Twins. After failing as a dreamworld, the "nightmare" Matrix was redesigned once again. As a result, the monsters were programmed for deletion.
However, before Cain, Abel, and some of the other programs were supposedly deleted, The Merovingian was able to save them from deletion. Upon rescue, the surviving Exiled programs started to work for The Merovingian, helping him and his wife Persephone, with continued service being guaranteed by the couple's knowledge of the Exiles' kill-codes.
Serving The Merovingian
For years, The Merovingian had locked The Keymaker in his Chateau. But Abel, together with his partner Cain, intentionally let The Keymaker escape from his prison beneath the Chateau in order to try and secure the key meant for The One outside of The Merovingian's circle of influence.
However, Abel foiled this plan by telling The Merovingian about the betrayal. This led to The Merovingian destroying the key, forcing The Keymaker to eventually create another one.
When Persephone led Morpheus, Trinity and Neo to The Keymaker's cell, she shot Abel in the head with a silver bullet, demonstrating the special method needed to kill a lupine program. This allowed the Resistance to retrieve The Keymaker.