In Part 4, Chapter 1, at a celebration at the French church, Amédée asks Emil for help with a prank the men are going to play on the women. Amédée does not realize the dramatic irony of his request:
The only difficulty was the candle in Marie’s [fortune telling] tent; perhaps, as Emil had no sweetheart, he would oblige the boys by blowing out the candle. Emil said he would undertake to do that.
The prank involves putting out all the lights at once; the men plan to take their dates by surprise, kissing them in the dark. There are some problems with consent involved in this prank, but the novel presents it as a bit of lighthearted mischief characteristic of Amédée. The reason Amédée gives for asking Emil to blow out the candle in Marie's tent is that Emil alone (having just returned from Mexico) does not have a "sweetheart," at least not one present at the church. He can take care of this loose end while the rest of the men pay attention to their dates.
Emil and the reader both know that it is not exactly true that he doesn't have a "sweetheart." Emil first left for Mexico to run away from his feelings for Marie. Now that he is back, Marie has been staying close by and showing a bit too much interest in him. His plan to kill their attraction to one another through his absence seems to have failed. Of course, Emil and Marie have been letting everyone else believe that they are simply lifelong friends rather than would-be lovers. Amédée's request puts Emil in a difficult position. For one thing, Emil is fond of Amédée and his mischief, and he wants to say yes to his friend. For another, telling Amédée that it is not a good idea to go into Marie's tent like this would involve admitting to their ongoing flirtation. This admission would be embarrassing and would also increase the social pressure on Emil to avoid Marie (something he knows he should do but that he would rather not). Finally, doing this favor for Amédée will give Emil the chance to sneak into Marie's tent under mostly innocent pretenses and to be right next to her when all the lights go out. This chance is too tempting for Emil to pass up.
Dramatic irony makes this moment both comical and tragic. It is funny that Amédée thinks this is an innocent plan. On the other hand, if he knew what he was asking Emil to do, he might have found another way that would not lead Emil and Marie into such a perfect trap for infidelity.
