Enjolras does look back, just one quick and sober glance sideways as he turns the first corner. He says nothing; he carries on, and the wall intrudes between, and the Minotaur doesn't follow.

He does, half a corridor later, glance at Grantaire, in the dim torchlight. It's a thoughtful look, and assessing.

(Up ahead, as they'll see when they round the corner, there's a Δ scrawled on the wall as if in white chalk.)