Geary's character began as a "hit man" and later as a rapist who fell in love and subsequently married his victim, Laura Webber (played by Genie Francis). The character became so popular that the writers turned Luke Spencer into a protagonist. Spencer and Webber's 1981 wedding began what was arguably the greatest love affair in the history of General Hospital, if not daytime television. The early 1990s saw Luke Spencer in a series of nearly improbable storylines seemingly lifted from the pages of a spy novel, which only served to further the character's popularity.

He also portrayed Luke's lookalike cousin Bill Eckert on General Hospital from 1991 to 1993.