I wouldn’t say he’s submissive toward Enjolras always. There are key moments where he explicitly sticks up for his own position to Enjolras’ face. The part where he prevails upon Enjolras to get himself sent to the Barriere du Maine, or the “Let me sleep here…until I die here,” bit. But the thing is, those moments? They’re key precisely because they’re exceptions to the rule!
I do think that if they interacted more directly more often, Grantaire’s penchant for quipping would come out more, but yeah, like. y’all. listen. listen. There is nothing in canon to suggest that Grantaire and Enjolras argue during ABC meetings! As far as we know, Grantaire never directly challenges his object of admiration while he’s soapboxing! At best, you can say that in the musical Grantaire adds a few funny comments that fit into the margins of Enjolras’ speech, but he doesn’t pick fights with the man. Doing that kind of shits-and-giggles pigtail-pulling in an actual activist meeting where people are trying to get work done is a surefire way to not get invited back ever.
Grantaire’s depressive rambling happens during backroom downtime, the same time other ABC members use for shooting the shit about plays and setting things on fire and giving each other advice about their respective mistresses.
In my opinion, at least, Grantaire is a lot more interesting when his snarky downer side is visibly at war with his “treat Enjolras with tender deference” side. If you personally want to write a story where Grantaire argues with Enjolras during meetings while Enjolras is actually taking point brainstorming strategy with the others, or while he’s giving presentations about upcoming events, or whatever, you obviously can – it’s not totally implausible, especially if you’re drawing heavily on the musical’s characterization of Grantaire – but please at least be aware that it’s a fandom trope, not explicitly justified by canon, and shouldn’t be taken as a given.
Listen, I love sweet, awkward Enjolras who has trouble with pda as much as the next fan but please imagine if you will a really, really adorably physical Enjoltaire.
Imagine Enjolras and Grantaire being unable to keep their hands off each other for more than a second or two (“We’re making up for lost time~!” R insists, with his boyfriend cuddled up in his lap). It gets absolutely ridiculous; Enjolras sitting in Grantaire’s lap even though there are plenty of other chairs he could be sitting in (which has absolutely nothing to do with the way R’s hand rubbing his thigh and cupping his hips), intense after-argument makeout sessions that make everyone in the immediate vicinity feel slightly dirty, Enjolras draped across Grantaire’s lap with the artist running his fingers through his hair and ranting to Courf about something then completely loosing his train of thought because ‘Taire tugged on his hair in just the right way and goddamn that felt good. The Amis are all torn between thinking it’s adorable and begging them to just get a room.
One time poor Marius forgot one of his textbooks in the Musain and went back after a particularly argumentative meeting. He was still bright red when he got home and refused to talk about what he saw.
¯_( ಠ_ಠ)_/¯ 