Massimo Marone was a childhood friend of Stephanie Forrester and an apprentice of her father, John Douglas, who was a powerful Chicago businessman. Massimo went to college at Northwestern University with Eric Forrester, Stephanie Douglas, Beth Henderson, and Stephen Logan. He dated Stephanie before she met Eric and while on a trip to Lake Geneva they slept together and conceived Ridge. Stephanie soon met and began dating Eric Forrester and when she realized she was pregnant she used it to get Eric to break up with Beth Henderson and marry her. Massimo, like Stephanie's father, didn't want Stephanie to marry Eric but everyone thought that Eric was the father of Stephanie's baby, so Massimo relented.
Massimo went on to build an international shipping company, Marone Industries, and ran it with an iron fist. Marone Industries earned a reputation as a very conservative company and Massimo became a very wealthy and powerful man with a reputation as a ruthless businessman that always got what he wanted. After Eric and Stephanie's first divorce Massimo became a confidant to Stephanie and continued as such in the years since then.
Massimo came to L.A. to pursue Stephanie and this caused animosity with Eric and Ridge. Under the influence of his feelings for Stephanie, Massimo collaborated to make arrangements for Brooke to leave and move to Paris. In Massimo's office Ridge cut his hand and needed a blood transfusion. Blood tests revealed that there was no way for Eric Forrester to be Ridge's father. Massimo reminded Stephanie of the time they were once together in college. Stephanie concluded that Massimo was Ridge's father. Stephanie asked that Massimo keep Ridge's paternity a secret. Massimo did for a year but was overheard by Bridget talking about Ridge being his son and soon Massimo told Ridge the truth about his paternity.
Massimo left L.A. for an unknown destination. Recently Nick and Stephanie told each other that neither of them knew of Massimo's whereabouts and neither has heard from him.