Ethics: after Worf dies. When Crusher walks out, tears in her eyes, to tell Alexander and Troi.
Chain of Command II: "THERE ARE!!! ... FOUR LIGHTS!!!" And when Picard recounts to Troi that at one point, he thought he could see five lights. That got a tear in my eye.
I'm surprised "ethics" would have that effect since the audience knows Worf isn't dead.