The central issue in the "Heroine" episode is the casting question, of who is going to play the role of Carmen. This question pits Shion, president of Spica, against Miyuki, head of Miator and the person in charge of all production issues. Shion wants Amane to have the lead role of Don Jose, against Shizuma’s Carmen, as a part of her larger plan to get Amane to run for the Etoile election. When Shion’s initial attempt to get Amane the lead is foiled by Kaname and Momomi’s undermining tactics, Shion then undertakes a private campaign of bribery (she gives Tamao the playwright cookies in an attempt to influence her to write the part for Amane) and public politicing for an Amane-Shizuma pairing. Shion hopes to use extrinsic pressure to force Miyuki’s hand.
In effect, Shion is trying to write the Carmen production into a larger story she herself is writing, with Amane as the star, and the greater glory of Spica as its purpose. The heroine in Shion’s story is really herself; and the story she is telling is about inter-school political rivalry, with political manipulation as its narrative content. We can see that the question of the heroine–understood in the larger context of Strawberry Panic itself, and not just of the play Carmen–decides the actual nature of the story that is being told.
If we look at "Heroine" from this perspective, we can see there are all sorts of candidates for heroine of the episode, and for kinds of stories struggling to be told. Kaname and Momomi tell Shion’s political story from the perspective of anti-heroines, who seek to destroy the production in order to displace Amane from the Etoile election. Tamao illustrates a story of literary stardom: her play gets chosen to be performed, she gets to write the screenplay, she is included in all major production decisions. In a reversal of roles, she is now the leading character vis-a-vis Nagisa, where before she had always been secondary. Amid all these political fights and production issues, the anime’s principal romances become a secondary story. Still, both Nagisa and Hikari use the production as a means of advancing their relationships, as when they plump for their beloveds to have major roles, in a show of partiality that also expresses their love, or when they help their beloveds learn and practice their lines, finding in the play the opportunity to spend time and grow closer with their beloveds. Evidently there are a multiplicity of stories contending for expression within the episode.
Thus, the social world we see dramatized in "Heroine" is a competitive, even antagonistic one, which is decomposed into individuals and factions, each struggling to impose its will on others. That this description holds for Shion, Kaname and Momomi is self-evident; but it is true even of Nagisa and Hikari, in their attempts to urge their beloveds to take leading parts in the play. For example, Nagisa tells Tamao she wants Shizuma as Carmen, just after Shion has tried to bribe Tamao to that end; and Hikari goes along with Shion’s urging of Amane to perform, despite Amane’s clear reluctance to involve herself. We have discussed this Clausewitzian theme in Strawberry Panic already, wherein society is war by other means: the current episode is this theme’s paradigmatic example.
As it happens, Miyuki rejects Shion’s plotting, and instead chooses Chikaru to be Carmen, Shizuma to be Don Jose, with Amane as Escamillo, Kaname as Don Jose’s superior officer, and Momomi as Micaela, Don Jose’s fiance. She justifies her choices to Shion based on the interest of the drama itself, as opposed to any extrinsic motive or purpose: "the Strawberry Dorms’ play isn’t a popularity contest. Our goal is to have a marvelous performance which everyone is happy with." We learn from Tamao’s words to Nagisa that Miyuki has chosen Chikaru since she had been the best actress in the previous year’s production; and as Shizuma says herself to Nagisa, it would be stale and repetitive for her to have the lead this year, since she had had it in the year before. As Tamao puts it, in an editorial comment that surely speaks for the anime itself, "Rokujou-sama really knows her stuff." While her choice is politically astute–she undermines Shion’s complaints by putting three students from Spica in leading roles–Miyuki decides primarily on aesthetic grounds, in terms of who will give the best performance.
By insisting on the aesthetic ideal embodied in the dramatic production, Miyuki seeks to transcend the social antagonisms brought into play by the casting issue. She chooses not one faction over another, but the play itself as a general goal toward which everyone can strive together. As we see in the "Behind the Scenes" episode, the production becomes the vehicle for general social harmony, as each person fulfills her assigned role and works together with others to make the play a reality. In this context, heroism becomes an exemplary dedication to the achievement of the larger goal. Thus, the anime approves of Tamao, for her dedication in writing the screenplay, and of Chikaru, who fulfills the combined task of preparing for the lead role and creating the costumes. If Kaname and Momomi are the villains for trying to halt the production, Nagisa and Shizuma are the heroines–in another instance of Nagisa acting as de facto Etoile–for standing up to the villains and rallying the students to overcome Kaname and Momomi’s sabotage. The aesthetic achievement of the play is the corollary to the social harmony and the individual heroism and self-sacrifice that make the play possible. It is these moral and redemptive qualities that are "Behind the Scenes," and stand as a decisive counter to the antagonistic conception of social reality offered earlier.
One last question: what does the play "Carmen" have to do with Nagisa and Shizuma’s relationship? It cannot be coincidental that the narrative contrives with considerable artifice to place Nagisa on the stage performing Carmen to Shizuma’s Don Jose. Part of the reason must be that we as viewers are to understand Nagisa and Shizuma’s characters in terms of the parts they play. When Nagisa proclaims as Carmen, "I am a free woman!," she is describing a crucial aspect of herself, which we have seen confirmed in other episodes. And it is easy to see in Don Jose’s self-destructive fixation on Carmen, his conviction that Carmen somehow belongs to him, an analogue both to Shizuma’s obsession with Kaori and the possessiveness she displays towards Nagisa. While the narrative of "Carmen" has little to do with Strawberry Panic–Shizuma does not kill Nagisa!–the play does dramatize the still-extant differences between our main characters.
Still, what counts about the play is that it provides Nagisa and Shizuma the opportunity to restart their romance after the failure of "Summertime," to bring it forward to the moment when they can play as lovers before the whole school, and finally to the last scene of "Behind the Scenes," where they are alone together in the greenhouse, and Nagisa can tell Shizuma how happy she was to be on stage with her, while they stand with hands entwined. Just as the play becomes an avenue for a general social comity, it makes possible the love of individual couples. The school bonfire, where all the students are gathered together, but with lovers and freinds gathered closer, is an excellent symbol of these multiple levels of unity. It is curious that Nagisa and Shizuma are apart from this social world, in the greenhouse. While Strawberry Panic celebrates social harmony, it recognizes the highest moments of love to be an intimacy that belongs to the lovers alone, in a world of each other, in a rarified world of art or nature. As the downcast faces of Tamao and Yaya at the bonfire prove, love finally leaves others behind.