When I recall the story of the ugly duckling, I don't seem to remember it correctly. When he turns into a swan, I don't feel like he remains a 'he', but rather, a more correct pronoun would be a 'she'. A swan, a symbol of femininity, grace. Long neck, riding on a slipstream of a micropocket of air above a pond. 'He' just does not fit. I envision the ugly duckling, now metamorphosed into a swan, a duckling trapped in a swan's body. He has grown, matured, turned full circle upon his self-image, except for the nagging loose thread, invisible to everyone except himself. He is still a boy, and what he fears the most is to become a man. A giant ugly duckling.
He could revert to Him any moment because there are no system of checks and balances to keep track of his inner mental state. People will admire him, other swans (and assorted flying creatures) will yearn to couple with him, to cradle their necks in heart-shaped patterns with her. But she, in the deepest recesses of her mind knows she was different once. The thought will crop up at the most inopportune of moments, while in the throes of passion, when she is in bliss flying with her newfound wings over vast stretches of unterraformed land.
And when she sees another ugly duckling the painful memory will rear its bite. She will be reluctant to have children, in case one of them may grow up to be like her. She will be torn between the motherly instinct and infanticidal father. You can always run away from a relationship, severing all ties in the process, mutilating yourself from the chains rusted from years of misuse, but you cannot run away from the man in yourself. You are part of a race of boys that transform into swans to sprout wings, only to fall to the ground.