He is none of them.
He is all of them and more.
And that dual existence, brought on by the Bleeding Effect where the memory of ancestor bonded with that of descendant, is what saved him in the depths of the Grand Temple. The machine that should have taken his life had gotten confused and instead had only nearly killed him, leaving him with severe burns and a lame hand to remember the ordeal by. It had also in the process merged the shattered layers of his mind, binding the past with the present.
The Abstergo fools that had come to try and collect his corpse had certainly gotten a surprise when he swept up from the floor to stab one of them in the throat with the broken remains of his hidden blade. They’d run after that, fleeing for their lives, and he hadn’t the energy to pursue them. It was better that way, however, as they would carry the tale of his survival to their fellows.
After he’d recovered, of course, he began the long task of fighting against Juno, seeking what information he could within the Temple before he ventured out. By then, he learned, the Assassins and Templars had formed a tentative working agreement in order to battle the greater threat while trying to learn each others weaknesses and how to exploit them later at the same time. He had sneered at the agreement because he had proof in his own head that such never worked out the way either side intended.
Haytham Kenway’s knowledge of the Templars had proven indespensible as, even with the years between them, the organization was still largely the same at heart. He had used that knowledge and more that he gained over time with ruthless efficiency, repeatedly infiltrating the Templar ranks (which was astoundingly easy despite them having his face everywhere) and very subtlety laying the groundwork for their demise. It was a beautiful construct and even Haytham was impressed despite the fact that it was going to destroy everything he’d built.
He managed to avoid Rebecca, Shaun, and Desmond’s father amongst the Assassins by simply not being there. Oh, he aided them in their endeavors and sent them the occasional mysterious e-mail with vital information but he never tread with them. It was too dangerous not only for himself and them but it would hurt all of them.
In the end, Juno was defeated at terrible cost to both sides. Thanks to his designs, the Templars appeared to destroy themselves and what remnants managed to survive scattered.
It was then, after those final days, that he sent an e-mail to William Miles requesting to meet him, promising precious information on the fate of his son.
Leaning back on the bench, he stretched out his legs and crossed them casually at the ankle. As he scanned the park, watching those passing by with his Eagle Vision, it wasn’t hard to notice when William was coming. Suddenly there was a blue spark amongst the grey world, glowing brilliantly as it strode casually forward.
He swept his gaze around, looking for any other spots of color, but none appeared. Letting the Vision fade, he waited until the older man was close before he lifted his head at just the right angle. It was the perfect one to allow most of his features to be revealed from underneath his hood and William’s shocked gasp echoed down through his core.
"Yes," he answered sadly, "and no." Standing up, he looked levelly at the man that was his father and wasn’t. "The machine did something unexpected instead of killing me."
William’s brow furrowed for a moment then he watched the man’s entire being seemed to shatter. As his shoulders slumped and his face went ashen, he breathed, “The Bleeding Effect.”
Nodding, he supplied, “It apparently confused the machine and kept it from killing me. Rather fortunately as well, it stopped my mind from tearing itself apart.”
"No longer myself?" He laughed dryly before continuing, "Far better than going mad."
William just stared for a moment before he nodded weakly. As he ran his fingers back through his hair, he asked, “Why meet me now? Why not come before?”
"Because we knew how much it would hurt. We have all lost."
"A wife," he said in Altaïr’s voice.
"A father," he said in Ezio’s.
"A son," he said in Haytham’s.
"A mother," he said in Ratonhnhaké:ton’s.
"Everything," he finished in his own natural voice, Desmond’s. William was shaking now and slowly collapsed onto the bench with the very real proof of what had happened to his only child. Slowly, he knelt next to the older man and quietly said, "I am sorry."
There was a choked noise in response then he was enveloped in William’s arms, the man’s beard scratching against his cheeks. For a moment he hesitated then closed his eyes as he lifted his own arms to wrap them around the other man.
"You’re alive," was breathed into his ear. "That’s what matters to me."
And that, in the end, really was all that mattered. He was alive.
They were alive.
Everything else could wait.