Headcanon that Enjolras is ridiculously ticklish, and Grantaire is the only person who knows this
And there’s this spot at the nape of Enjolras’ neck, and another behind his right knee, and - Grantaire’s favourite - one on his stomach, just below his belly button, and all Grantaire needs to do is blow on the skin there, and Enjolras becomes squirming, giggling, whimpering putty in his hands