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It takes decades for Daisy and Benjamin to finally fall in love with one another. Ironically, it is short-lived, as Benjamin decides to leave Daisy rather than cause her any more pain than in necessary for her and their daughter.
Father
Benjamin is invited out for drinks with a gentleman in New Orleans one night, and they have a long talk over many cocktails. Ironically, the man is Benjamin's father and he doesn't tell him his identity until much later in his life.
Old Age
Benjamin grows up in a retirement home. Ironically, he is getting younger as everyone else is growing older. But the real irony is that he learns the value of loss far sooner than many ever have to experience and thus the value of relationships and life which he carries with him into the rest of his years.
Relations
Benjamin tells the Captain that he's never been with a woman, which is unbelievable to the sailor. So, he pays for Benjamin to sleep with a prostitute. Ironically, he doesn't know that Benjamin is a mere teenager in the body of an old man.
Caroline
Caroline is only told of her father at the end of her mother, Daisy's life. Ironically, Caroline met her Dad when she was younger at Daisy's dance studio when Benjamin arrived years later to check in on Daisy, and Caroline wasn't told until the very end of her Mom's life.