smoking headcanons? idek why I even have these, but
Feuilly, Grantaire and Prouvaire smoke cigarettes; Bahorel used to but quit before he met Les Amis. None of the others smoke. (Enjolras in particular hates it.)
Prouvaire, Grantaire, Joly and Bossuet smoke weed from time to time, Prouvaire the most often, the other three when they’re together.