He knew, before he started talking, that this might not get grasped the way he wanted. Morpheus was more human than Cas, in a lot of ways.
"Well."
He crossed his arms, bringing one hand to his chin and rubbing at it. "I'm what I am because I'm good at acting human. But I'm not. Other gods... you feel that shit, when they walk into a room. Enyo, for example." He suppressed a shudder. He shrugged. "I'm not very god-like. You... it's the same feeling, I think. You look human, but you're not. And you're not quite angel enough either to be one of those anymore."
You are associated with dreams. Yes?
He nodded. "King of." Morpheus gave a slight bow. "Brothers do nightmares and phantasms. And there are billions of us, the Oneiroi. Every one can weave dreams. I'm just in charge."