Fifth Profession

Blurb

The Fifth Profession is a 1990 novel by David Morrell. It features the characters Savage and Akira, executive protectors – "no mere bodyguard[s] but... state-of-the-art defender[s]", an occupation also known as the "fifth profession".
Savage and Akira meet − seemingly for the first time − by Savage being dispatched by a Joyce Stone to liberate her sister, Rachel, whom Akira is guarding against that eventuality. Their brief clash triggers off memories of a previous meeting, where each believed he saw the other die in the course of a prior mission of protection together; memories that are quite obviously false, but that both believe to be entirely real. The two join together to uncover a string of other falsified memories, taking Rachel Stone with them – thus fulfilling both protectors' missions; Savage's to retrieve her, and Akira's to protect her.
This is a phenomenon that Savage identifies as jamais vu, a familiar situation not recognized by the observer.