No offense but instead of having badass Cosette and Marius clumsily trailing behind her how about:
-Cosette and Marius having a thousand of inside jokes and always making eye contact and going like “EYYY” (usually internally, but not always) when someone unknowingly makes a reference one of them
-Cosette and Marius having secret handshakes that top all secret handshakes ever
-Marius realizing that Cosette is actually a totally chill and awesome and nerdy person and becoming completely comfortable around her
-Cosette finding Marius to be the best friend she never had and enjoying every second they spend together
-Marius and Cosette being the picture perfect couple. Like, they have an elaborate picnic complete with champagne and a homemade quilt and both of them looking drop dead gorgeous and they’re like “yeah we were bored lol"
-Cosette being super supportive and helpful while Marius deals with his anxiety
-Marius introducing Cosette to more friends than she ever had in her lonely, isolated childhood
-Marius and Cosette teasing each other
-Marius telling super cheesy jokes and pick up lines and Cosette adores every single one and snorts from laughter each time
-Cosette and Marius being super gross in public just to embarrass their friends
-Cosette and Marius having an open, healthy, happy, hilarious relationship