Moore based him on real poet W.B. Yeats.
An Irish Wagnerite, Dean has believes in Christianity but also in Celtic pantheism: "the ancient gods Angus and Lir, and the Great Mother Dana...."
He has a fling with the title character/opera singer Evelyn Innes even though she's engaged to baronet Owen Asher.
He composed the opera Connla and the Fairy Maiden, and composes the opera Grania inspired by Eveyln, who was to sing the lead role before quitting opera altogether.
He had one of those long Irish faces, all in a straight line, with flat, slightly hollow cheeks, and a long chin. It was clean shaven, and a heavy lock of black hair was always falling over his eyes. It was his eyes that gave its sombre ecstatic character to his face. They were large, dark, deeply set, singularly shaped, and they seemed to smoulder like fires in caves, leaping and sinking out of the darkness. He was a tall, thin young man, and he wore a black jacket and a large, blue necktie, tied with the ends hanging loose over his coat.