The makeup they used to make their face pale and luminescent reflected the fire. Remus was transfixed by the sight. With each flicker, it looked like they were glowing from within, like they  were  the fire. Even more than he had wanted to catch the embers before, he wanted to catch Sirius. When they laughed, he wanted to laugh along with them. When they were upset, he wanted to comfort them. When they glowed, brighter than the stars, Remus wanted to be there to encourage the flames, to bask in them, to burn in the light. 