it annoys the hell of me because then people are like "Marius should be with Eponine" when they see the musical

Remember how when Marius was living in a small room he could see through a hole in his wall into the other flat where the 'Joselles' (I think that was their name) lived who were the Thenadiers! They changed their name to squirm out of all their debts. They took it back. Yes as you say Eponine should have been with Marius as they were friends. It was sad how she had to die but as she said 'I'll sleep in your embrace at last'

For your information, M. Thénardier chases after Valjean and Cosette with a gun in the book. Yeah...

*Javert sorry had to say it

Eponine was insane(ish) in the book. She took Marius to the barricade to die with him. In the musical you get none of that obsession. This is neither a good or bad thing, it is just fact

I HATED Marius in the book, his sense of morality only clung to his dead father's last wish to help the man who helped him [Thénardier] and he does this through the whole book even after knowing he's a thief and prospective murderer (even to the point of helping him financially when he's arrested by Jarvert) but has the gall to turn JVJ away from Cosette (granted JVJ went willing because he's freakin' Christ in the book) and wouldn't except his money because he thought "it was ill received" but some how helping Thénardier is just fine. WTF? And i don't even want to get started on his relationship with is grandfather...
The musical made Marius seem like a decent human being, and I much prefer its ending to the book's.

Well in the book she is much tougher and less calm, like how she constantly rants for pages on end and spits on valjean

"Javier" bwahahahahaha

In the book, (though I haven't read it only heard things from it) Marius is polite to her but dislikes Eponine. In the musical they are portrayed a best friends.

Éponine in the musical is a lovely character, a person whose heart is broken but who has good feelings however in the novel is selfish and never did anything with good intentions

MissSaigon, the name that Thénardiers used was Jondrette