Excellent. 

After the food is eaten and the leftovers packed away, Samora starts up a Marching Chant. The incantation is less like a sentence than a song, at times wordless, at times telling the party of their own strength and endurance with a bright, clear tune that makes it easy to believe. Jogging along deer paths and stomping through underbrush becomes as easy as walking up a well-made road. 

The food is good, but the song is lovely.  Marc hums along happily for a long while, until it's been enough hours without a conversation that he wants to talk to someone more than he wants to enjoy the music and the wonderfully effortless movement.  Not that he can exactly have a conversation, with Samora busy with her magic, but it's not very hard to get the more talkative hobbits to teach him some words in the local language as they walk.  He doesn't remember them perfectly, but he picks things up well enough over time, enjoys the interaction, and doesn't mind being laughed at when one of his mistakes turns out particularly funny.

The ability to say "I am walk many fast" isn't going to be very much use even once they correct all his grammar, but once he has even a bit of the language, it'll be easier to pick out more just by listening to everyone talk.

The hobbits thinks his accent is hilarious and are happy to do language lessons until they stop for supper and sleep.

This time Aragorn trusts Samora's qualifications as a watch-stander enough that he and Marc can get half a night of sleep each and still have coverage in two directions. Does Marc want first half or second half?

Oh good!  He'll take the first watch – the Sun here goes down earlier than his own did, so he's not sleepy in the evenings anyway. 

(He tries to explain this to the hobbits in Westron, for the sake of practice, and they all get into an entertaining muddle about it until Samora rescues them.)