When Brian first appeared on the scene, he was a fisherman in Bermuda who just happened to find Sheridan Crane floating in the surf. He began to care for the unconscious woman, and before too long, found himself falling in love with her. When she woke up, they discovered that she had amnesia. She called herself Diana, a name that meant a lot to her. Brian spent a lot of time with Diana, and soon realised he was completely in love with her. She doesn't return his feelings, but she doesn't reject them. When Brian was asked to take a woman's boat back to Harmony, he initially refused, only agreeing when Diana begged...he just couldn't say no to her. He has no idea what's awaiting her in Harmony...but there is something awaiting him there as well.

On a practice boat ride, it was revealed that Brian O'Leary was really Antonio Lopez-Fitzgerald, the long-lost son of Pilar and Martin! Antonio had disappeared as a child, before he was even a teenager. Martin had vanished without a trace when Antonio was only 10, and he had soon followed in his father's footsteps...whether to find him, or to escape the responsibility of his younger siblings is uncertain...leaving a 7-yr-old Luis the 'man of the house'. Nearly eighteen years passed before Antonio had contact with his family again. (Note: That may have changed now to an 8-yr-old Luis, and a nearly seventeen year absence.)

Despite many reservations, Brian has agreed to take Sheridan to Harmony. When he arrives, he is assailed by memories of his former life. He refuses to go into Christmas Eve mass, but does go to the Lopez-Fitzgerald family home that night, and while Pilar sleeps, tells her how much he loves her and how sorry he is that he ran off on the family. But before he gets a chance to actually talk to her, he has a run-in with Ethan, and flees.