That's neat. I love her name, but the only thing it made me think of was "marionette" like the puppets with strings.
Is there actually an "a" in her last name? I thought it was "Dupin"-Cheng (which is indeed pronounced "Du-pan"), after the first fictional detective character, Auguste Dupin (who served as a model for Sherlock Holmes). Auguste Dupin is a Parisian detective and the hero of Edgar Allan Poe's "The Murders in the Rue Morgue", which is considered to be the model for the first mystery story of crime detection featuring a rational detective who is able to put together clues based on evidence which goes entirely unnoticed by others.
Oh, and I meant to say nice work on translating the roots of the French words. I hadn't really thought about looking into that angle. It's cool how they can have these things that have double meanings so it both refers to Marinette's personal heritage as the daughter of a baker, and to a famous (fictional) Parisian detective.
Oh, and I since I mentioned him above, I just remembered that Sherlock Holmes also lived at the address 221B Baker Street.