Sheila mentions Eric Caswell in the story because although she is going to the dance with the narrator, it is Eric whom she is really interested in. The fact that she talks about Eric while she is on the way to the dance with the narrator, coupled with the indifference of her behavior in general, should have forewarned the narrator to the reality that Sheila was just using him, but he is so enamored by her glamorous allure that he fails to see that his brief courship can only end in failure.
One of the first things Sheila tells the narrator on the canoe ride to the dance is that "Eric Caswell's going to be there." She later relates that "Eric said (she has) the figure to model;" it is clear that Eric is much on her mind, even though she has consented to go to the dance with the narrator. The extent to which Sheila has set her sights on Eric Caswell becomes completely evident when she goes home with him instead of her date.
There are many instances of suspense in the story. One of them occurs when the narrator first hooks the bass, and realizes that "it was a bass...it was a big bass...it was the biggest bass (he) had ever hooked...Sheila Mant must not know." The narrator struggles to hold on to the bass without letting Sheila know what he is doing, but fortunately, it turns out that she is too busy talking about herself to notice his preoccupation. A second instance of suspense is when the narrator realizes that he must choose between letting Sheila know what he is doing, and letting the bass get away. For an instant, the narrator is "torn apart between longing," but the scales tip in Sheila's favor when he looks at her attractive figure, and he quickly cuts the line in half, in a decision that he will forever regret.