Oh well, I don't think anyone would mind a Grease AU with the roles reversed. I mean, Aaron did great but technically if I had to cast him for any part in the show I'd go for Sandy for him ;)
Honestly, if I were to write a full Grease AU, neither Enjolras nor Grantaire would step into Sandy/Danny’s shoes. Instead, I’d go with Kenickie for Enjolras and Rizzo for Grantaire, while Marius becomes Danny and Cosette Sandy.
Bear with me on this, because with some broader changes to structure, I promise it’d make sense – the T-Birds and Pink Ladies are no longer separate groups split by gender (because I mean c’mon), but instead one big group, Les Amis (”We ain’t no gang,” Courfeyrac reassures his latest conquest, leaning against her locker and winking broadly as he adds, “but we ain’t no French club either”). Their Scorpion rivals? Why, nothing more than National Guard ROTC kids from a neighboring school.
Danny!Marius’s acting one way around darling Sandy!Cosette during the summer and a whole different way around his friends at school suddenly makes a lot more sense, especially when, Red and Black-style, he’s mocked mercilessly for it (”Look at me, I’m Pontmercy,” Grantaire croons to general laughter, “I ‘oo’ and ‘ah’ like an opera scene!” Enjolras tries to ignore him, but fails, instead choosing this as an opportune time to lecture them all about the importance of the upcoming race against those National Guard goons).
Their school’s national tv appearance on Do You See the People Dance? goes not at all as planned – Grantaire brings Éponine, who’s still in love with Marius, while Enjolras agrees to let Le Cabuc come as his “date” since he couldn’t get a ticket (”Because he doesn’t even go to this school,” Grantaire complains bitterly to Éponine, who’s not listening to him, watching Marius and Cosette dance. Meanwhile, across the dance floor, Le Cabuc is picking a fight with a kid named Porter and punches him, which makes Enjolras punch Le Cabuc and kick him out of the dance).
It’s obviously not Rizzo’s possible pregnancy that brings the two together finally, but rather a quiet moment following the eventful car race – the race that Pontmercy wins, not Enjolras, stepping up after Enjolras gets injured and taking his life into his own hands in the process after he thinks that he and Cosette are done. (”Good race,” Grantaire offers, sitting down next to Enjolras, who looks worse for the wear, and not just because of his concussion. When Enjolras just grunts in answer, Grantaire tells him, “You’d have won, too, if you had been driving.” Enjolras glances over at him. “You think?” he asks, a little skeptically, and Grantaire just smiles. “Yeah. I believe in you.”)
And perhaps even more importantly, to address my least favorite part about Grease, Cosette doesn’t need to change everything about herself to officially win Marius (nor does Marius attempt to join a sports team which somehow equates to the same thing??) and (keeping with the original musical’s version where “You’re the One that I Want” doesn’t exist), “We Go Together” ends the whole thing nicely as Les Amis comes together one last time to celebrate their victory over the National Guard and their entire group pairing off together (”Yeah, because nothing really captures the spirit of your eloquence and speech-making skills like ‘shoobop sha wadda wadda’,” Grantaire mutters in an undertone to Enjolras. who just laughs and kisses him.)
That is how I would write a Grease AU. If I were, you know, so inclined.