If I recall correctly, that kiss on the head was totally unscripted.Call to Arms
Quark comes up behind Rom, who is busy modifying the station's systems ahead of the Dominion attack. They debate why Rom hasn't left and why he is helping the Federation. They both claim they are looking out for each other.
Quark says, "Well, like I said, you're an idiot."
And then he kisses him on the head.