Yay, THIS is truly a topic for me!
I'm sorry it took me so long to be able to finally contribute.
But that said:
You have all very good points here! And I'm saying that being a huge Éponine fan (nah... who'd have guessed?! *lol*) but non-bopper. ^^ Yes, it IS possible indeed. Just believe me.
I have to admit: I totally agree with you about the things you stated. To me, Éponine isn't an idolized beauty, nor a Misery Sue, as it's been called. She is a very complex character and her actions, especially in regards to Marius, are far from unselfish. Her life IS pretty hard, no doubt about that, but she still doesn't wail about it the whole time. Sure, she'll pretty sure have her moments when she reflects her life and conclude that it's not fair but ultimately I think that she has come to terms with her life and situation.
The relationships between her and Montparnasse and her family are very difficult and a lot is left open for interpretation here by Hugo, I think. There are vague suggestions here and there but in the end, it's true: Éponine is too "insignificant" (meaning that she indeed is no main character) relating to the whole book, to be clearly observed. What I mean by that is that we don't have that many situations in the book that focus on her and that could tell us more about it. In fact, there IS no scene where she, for example, gets a thrashing from her father or where she IS traded to Montparnasse or the Patron Minette and where she is with them on that purpose. (Or am I wrong here???)
It's all just hints and suggestions.
So my conclusion about book Éponine is, that she is not the most precise character there is in the book and not by any stretch of the imagination one of the REALLY important ones (although, of course, she has her share in the story). There is much space for imagination and interpretations which, as we all know, has inspired lots of fanfics. To me, she still is an adorable character though. Even in the book. xD She definitely has her moments (although, lets face it: she is somewhat loony... isn't she? kind of? *bg*)!
As for musical Éponine...: now that you mentioned it, it really is alarming how much all her existence is connected with Marius. It's really like he's the only reason for her to exist in the musical. It's like, in terms of the storyline, her existence is purely justified to "serve" Marius. I hope you get what I mean for I'm not sure whether I was able to express that correctly.
I never realized that so immensely as I do now. Well, maybe it's actually not THAT extreme but still: the way her whole role is constructed in the musical she really is all about Marius and her unhappy and unreturned love for him. So I totally agree with Lara here! She should have a pre-in-love-with-Marius scene or at least an additional scene within the current frame that has nothing to do with Marius. Like another intercation with her family or the Patron Minette that has nothing to do with Marius. Or perhaps a scene with Gavroche. THAT'd be adorable. And another benefit of that would be: also solely musical fans would become aware that they're actually brother and sister. xD (Okay - on the other hand that might probably raise questions as to why the Thénardiers don't care a bit for him and why they have nothing to do with each other really - but hey... that'd be solvable, somehow...) I'd love that! Maybe an encounter at the barricade or something. Or just a random errand scene or so. You see: there would be SO many possibilities.
Well, that's all I can think of to say for now. So... maybe some of you agree or disagree?! Come on, lets keep this going!