In Anton Chekov's play, "The Bear" (also known as "The Bear: A Joke in One Act), Luka is present to provide a characterization of Popova and to accentuate the comic elements of the play.
At the beginning of the play, Luka is trying his best to get Popova, his mistress (he is a servant), to go outside. She has shut herself inside for seven months in mourning a husband who was a unfaithful, cruel cad ("jerk"). Though Luka implores Popova not to waste her youth on the memory of such a man, Popova refuses to be swayed.
Once Smirnov enters, however, Luka first is running back and forth waiting on their visitor. When he tries to put Smirnov in his place, the "bear" threatens him and Luka backs off. While Smirnov and Popova are fighting Luka keeps up a commentary either by what he says or how he acts which further elucidates the interactions taking place between his mistress and her "guest."
When Popova asks Luka to show Smirnov out, Smirnov threatens him and Luka stumbles, grasping at his chest (physical comedy):
Shut up! Who are you talking to? I'll chop you into pieces!
[Clutches at his heart]
Little fathers!... What people!...
[Falls into a chair]
Oh, I'm ill, I'm ill! I can't breathe!
Because of the angry repartee passing between Smirnov and Popova, and because we actually see Popova finally caring about something other than mourning, we can't take Luka's illness too seriously. And his repetition of "little fathers" further entertains.
Their fight escalates. They are now hurling insults back and forth between them. Popova calls Smirnov a bear, a brute and a "Bourbon." She taunts him with, "Bear! Bear! Bear!" He becomes so enraged that regardless of the fact that she is a woman, he challenges her to a duel, spouting something about "equality of rights." Comically, she accepts, shouting that she cannot wait to shoot him in the head for being so stupid. She tells him:
I shan't have any peace until I've made a hole in your forehead... that forehead which I hate so much!
All the while, as Popova moves in and out of the room, Luka begs Smirnov not to fight with her. Luka is a sounding board for the benefit of the audience: Smirnov hardly knows Luka is there but he speaks to him. As Smirnov goes over what has been taking place, he first finds that he likes her. He admires her spirit. Soon, he is in love with her, and tells Luka that he will only fire into the air.
In full-blown hilarity, Popova enters with the guns, which Smirnov has to show her how to use. When he says he will not shoot at her, she is infuriated, certain that he believes her to be weak. Then she is insulted when he says that he likes her.
He likes me! He dares to say that he likes me!
Regardless, she still intends to shoot him. In the midst of this mayhem, Luka goes out to enlist the help of other servants to stop the duel. The comedy is complete when Luka enters with others to save Popova, only to find her kissing Smirnov.
Luka not only introduces Popova's character and state of mind at the start of the play, but he acts as a prop—"a person or thing serving as a support." Luka is an actor who not only "receives" the humorous lines of others, but reacts to them to accentuate their comic nature—while he observes the changes in the relationship between the two main characters, also showcasing the verbal and even physical humor on stage.