The mercenaries make their first appearance toward the end of the mission where Avon and Cliffford dispatch them to kill the protagonist. Their rise to power is made possible because Avon Hertz successfully manipulates Lester Crest and the GTA Online Protagonist into uploading Cliffford to the Ramius' mainframe, creating a path for Cliffford to hijack everything without resistance.
Clifford Mercenaries are speculated to be cyborg clones 'created' during the mission The Bogdan Problem by the Cliffford supercomputer after it successfully takes control of all systems aboard the Ramius ( Bogdan's submarine), the International Affairs Agency, a nuclear missile base inside Mount Chiliad, and the entire San Andreas defense network.