U.N.I.T. and Torchwood
Speaking of "U.N.I.T. dating", what about U.N.I.T. and Torchwood dating? I'm sure they had to have met in the field, argued about boundaries, saved each other's lives, helped each other out, practiced some one-upmanship, gone out for a drink, traded tips and war stories, found a room somewhere, and practiced some more one-upmanship.