Eren loves the body beside him. Not nearly as much as the person himself, but there's something about exploring Levi with his lips that enraptures him, the way Levi loves making him blush, loves studying the graceful slant of his shoulders and the delicacy of his collarbones.
"Beautiful," Levi murmurs sometimes, as his pencil whispers the soft edges of Eren's chest and the harsh lines of his hipbones. He's pathetic; he can never say it out loud, really, and he doesn't even say it properly. He's thought it a million times. You're beautiful. I love you so much. But it never escapes his mind. Instead he ends up saying something harsh or not saying anything at all.
But Eren never seems to mind. He simply nuzzles Levi's shoulder or kisses his neck and lingers there, and they're so obviously in love that it doesn't seem to need to be spoken.