Deep Space 9 is fondly remembered for many things, but the romance between Worf and Dax was a fan favorite. Surprisingly, it wasn't planned.
Originally from The Next Generation, Worf joined the cast of Deep Space 9 in season 4 to help give a ratings boost to the show. A romance for his character with one of the existing cast wasn't expected.
Terry Farrell have said the idea was all theirs. Farrell had joked that she and Dorn's character should flirt together so they both would more scenes.
The first scene the two meet is also the first time Dax tries flirting with Worf. One of Dax's past hosts is revered by the Klingons. When Worf mentions this, Dax responds in Klingon, essentially saying, "
Yes, but I'm a lot better-looking than he was " to which Worf awkwardly replies "I suppose so."
The chemistry between the two characters was apparent, two years later Dax and Worf were married, much to fans delight...until the tragic demise of Dax at the end of season 6.