Cosette keeps her feelings hidden, and Marius makes an ass of himself over and over. Hugo says it’s a rule that in these sort of courtships, “the girl never falls into any trap and the young man falls into all of them.” Valjean is convinced that Cosette has no clue who Marius is, so he starts looking daggers at Marius while Marius is making goo-goo eyes at Cosette. At one point, Valjean glares at Marius in a way that “even he could not fail to notice.”
It’s like an eye conversation.
Marius’ eyes (shouting): I LOVE YOU!
Cosette’s eyes (whispering): I love you too.
Valjean’s eyes (whispering coldly): Stay the hell away from my daughter.
On Tumblr (Re-Reading Les Mis)