 Both shows are set in Chicago and Derrick, a recurring character played by Stephen Guarino, appears on both shows.Three of the original six series regulars on "Marry Me" – Casey Wilson, Ken Marino and Sarah Wright Olsen – also appeared on "Happy Endings", albeit in different roles.John Gemberling, also a series regular, appeared on "Happy Endings", however as his character wasn't named — he was merely credited as 'Thief' — it is unclear whether the two characters are considered separate people.