ferretrade:

when they get engaged, marius totally sits cosette down all serious-like to let her know that he’s willing to change his last name if she wants. or she can take his. or they can be the pontmercy-fauchelevents. or fauchelevent-pontmercys. but those are a mouthful, really, and probably too hard for their future children to learn to spell in kindergarten, let alone have to bubble in on standardized tests in older grades.

and cosette is utterly charmed as usual.