The simple answer is he was Anna's partner at the DVX.
The long answer requires a little history lesson.
In 1980 Robert Scorpio appeared in PC. He was a crack agent with the WSB (World Security Bureau). After helping Luke save the world from the Cassadines in the Ice Princess s/l, he decided to stay and over the next few years, was involved (along with Luke) in helping the WSB save the world (or at least PC) from several threats. Among these threat was an agency known as the DVX.
In 1985 Robert prepared to leave his job as Police Commissioner and returned to Australia with wife Holly. His trip was delayed by the arrival of 7 year old Robin Soltini who had been kidnapped from camp and left on Robert's door. Anna arrived soon after and we learned that Robin was Robert and Anna's daughter from a brief marriage while they wer both working for the WSB. After making sure that Robin was safe and solving the mystery that had brought her to him, Robert departed to Australia to join Holly. Before leaving he made sure that Anna was appointed co-police chief.
Over the next five years Anna met, fell in love with and married then mob boss, Duke Lavery. Eventually Robert returned to PC after the death of his beloved Holly in a plane crash.
In 1990 Duke died in Anna's arms as a result of a mob war. Robert accompanied her to Scotland to scattered his ashes. They recalled their brief marriage and Anna spoke of her partner in the DVX, Cesar Faison. Anna hated Faison. She blamed him for forcing her into their last mission and for Robert learning of her life as a double agent. Robert had ended their marriage when he learned of her double life. Meanwhile Lila Q's favorite writer, PK Sinclair was making arraingment to move to PC. He rented Windemere (on Spoon Island) from Ned. In a storyline that involved Robin, a Space Alien named Casey and crystals. We learned that PK Sinclair was in reality Cesar Faison. Eventually Faison captured Anna, Robin and Casey. he used the space crystals to cause a major blackout in PC. Frisco & Robert helped rescue them and Casey returned to his planet. Faison was still a threat (he knew about Anna's treason). however he was still inlove with Anna and they used that to trick him into revealing damaging info. on the top DVX heads. When the DVX sent their top agent after him, he left town to safe his own life.
In 1991 Faison returned (still in love with Anna) just in time to disrupt newly reconciled Robert and Anna's wedding. This time he was involved in a mind control scheme with his new partners, Leopold Taub and Harlan Barrett (Brenda's father). Eventually their plot was brought to an end by Robert and the WSB. However, Faison managed to escape with the promise that he would return - for Anna.
Faison returned in 1992 in a s/l that involved the return of Robert's long presumed dead (but still legal) wife, Holly and something called the Sphinx stamp. The Sphinx contained a hidden microchip with info on something called the "Nanny Network". Faison, still obessed with Anna, managed to kidnap her. Knowing she would never be happy away from Robin he also made several failed attempts to kidnap her. Robert finally managed to figure out what had happend to Anna. Sean (Donnelly) informed Robert that the WSB had learned of Anna's actions as a double agent and put a price on her life. Before leaving to search for Anna, Robert informed Holly that though they were still legally married he loved Anna and was going after her and had started divorce proceeding for their marriage. He also asked his younger brother Malcolm "Mac" Scorpio to take of Robin, since the price on Anna's head made their return to PC unlikey-ever! Mac and Holly discovered (hidden on the mirco chip) the truth behind Anna's past, but determind to keep if from Robin, they managed to cover it up. By hacking into the WSB's main computer they learned that Robert and Anna were BOTH considered as good as dead by the agency. They rushed to Sean Donnelly (formerly of the WSB, currently PC Police Commissioner) for help, only to learn that the WSB had report and explosion on Faison yacht with Faison, Anna and Robert all aboard. No bodies had been recovered. All three were dead. Robin took the news well, considering. Holly, who stilled loved Robert tore up her divorce paper, UNSIGNED.
And so they all remained dead - until Anna resurfaced in Pine Valley 2-3 years ago. Evenually she reunited with Robin (who was in Paris) though they both believed Robert (and Faison) had died in the explosion. We all learned that was not correct when Robert returned to PC earlier this year in a s/l that involved Luke, a chimp and a deadly virus!.
With Anna & Robert surviving the blast, can Faison be alive too? (YOU BET!)
Know this was TOO long but hope it answered the question that was asked!