Their last partnership may have ended in divorce, but Rick Fox and Vanessa Williams are making another go at it – at least onscreen. Fox, 38, will join the cast of ABC's Ugly Betty in its second season, a source confirms to PEOPLE exclusively. "Things get heated [between their characters]," the source says of Fox's guest-starring role. Williams, 44, who got an Emmy nod for her turn as villainous magazine editor Wilhelmina Slater, can look forward to bossing around her ex-husband. "He'll be playing Dwayne her bodyguard," the source says. "He'll be there for at least two episodes."