In Resident Evil 6, you can play one of my personal favorite ways to play video games.. split screen co-op, or as I like to call it.. couch co-op.
To start a local split screen co-op game, you need to either start or continue your campaign. Keep clicking through the screens until you get to the screen where you select Difficulty and Screen Mode.
Change the Screen Mode setting on this screen from Single to Split.
When you accept the Split setting, it will take you to a screen where it will allow both of you to fight over which one gets to be the primary character, so Rock-Paper-Scissors-Lizard-Spock for it, or Roshambo for it, whatever you typically do to settle domestic disputes in your establishment.