Spending sleepless nights on the roof, talking about space and mythology and aliens
Grantaire helping Combeferre study anatomy because it’s interesting and useful in exchange for help on his math homework
Ferre allowing himself to be dragged out to parties he normally wouldn’t attend because Grantaire is going and is by himself and SOMEONE has to make sure that man makes it home in one piece
Constantly sharing sci-fi/fantasy books
Star Trek and Lord of the Rings marathons
They pass notes in Elvish during meetings, and it’s SO frustrating
Combeferre tried to one-up Grantaire once by writing Black Speech (orc) in Elvish script and got back “You fool no one” in Nordic runes
They poured hours into the structure of the Ancient Language from Eragon to make it a functional form of communication
Grantaire is a dirty memer, and so is Courfeyrac. They go back and forth all the time. Grantaire whispered “here come dat boi” when Enjolras walked in one day, and Combeferre scared the shit out of him because no one was expecting the “o shit whaddup” to come from him.
“Just because” experiments because Combeferre will do a lot of things ~for science~ and Grantaire is more than ready to get involved in something fun and potentially risky
“Grantaire, what fucking Hogwarts house do you belong in?” “Which one do you think I belong in?” “Stop doDGING THE QUESTION”