The Keymaker (sometimes spelled Key Maker) was a program created to open up the door to the Source for The One. In the Sixth Matrix he was kept prisoner in the Chateau of the Merovingian, during which time he saved Niobe and Ghost from an Agent. Morpheus, Neo and Trinity, with the help of Persephone, manage to free the Keymaker. While he was imprisoned, Abel and Cain let him escape, allowing him to save Niobe and Ghost from an Agent. However, Abel foiled the betrayal, found him in the hallways
The Twins, Matrix Wiki
Persephone, Matrix Wiki
The Second Renaissance, Matrix Wiki
Apoc, Matrix Wiki
The Merovingian, Matrix Wiki
The Matrix Reloaded - Wikipedia
The Matrix (franchise) - Wikiwand
Why is the Keymaker Important?
The Matrix: Original Motion Picture Score, Matrix Wiki
The Architect, Matrix Wiki