A/N: After seeing At World's End, I was struck by how Will did not choose his own fate, but rather had it thrust upon him by Elizabeth and Jack. From that grew this.
I am mostly guessing on Elizabeth's age.
Disclaimer: Pirates of the Caribbean belongs to Disney, not me. Duh.
Decades
When she was twenty-three and he just the same, she was vibrant, bursting with an energy that made her glow in a crowd, standing out like a single glass bauble glittering in the sand. Her eyes gleamed as they roved over his face and her hands clutched his flesh hungrily. She was a breath of fire that made his blood boil and burn, the only thing that could. She was beautiful. She was powerful. She was his world, and he hers, and when they parted with a desperate kiss they wondered how they could possibly live without the other.
When she was thirty-three and he just the same, her hands were callused and her limbs sinewy muscle, her skin darkened from years in the sun. But her eyes were no different, and when they saw him they filled with tears. The child he knew immediately, tracing the line the of a jaw he recognized to be his own, but the boy only stared back at the stranger called 'father,' his small face devoid of expression. The man fetched the child's grandfather, and the he was passed from one strange set of hands to another like fragile parchment. But as the sun reached its zenith, the boy was left, and the lovers spent the day in each other's arms, trying to forget the time that had passed. And when they parted, it was for her like losing him all over again, and she almost threw herself into the sea to join him.
When she was forty-three and he just the same, he found her alone. Her boy was a man, she said, and had left to find his own life, away from the sea and its demons. She'd had other lovers, though never other loves, and they had left their mark. And if her husband noticed the lines on her skin, the roughness where there once had been soft, the sagging where there once had been smooth, he gave no sign. And once, perhaps, she would not have either. But now, his fresh face, untouched by time and sun and salt, threw her faults into sharp relief, and the years that had sprouted in between weighed on her back. "I love you," he said. "Only you." She was tired, and told him she was no longer young. He looked in her eyes, moving the hand that shaped his fate over the old scar. "Elizabeth," he whispered. "What did you expect?"
When she was fifty-three and he just the same, she was gone, and he fell to his knees, crying with the only pain he felt anymore.