Castiel looked at his father as he spoke, and though conflicted feelings rose up in responce to the words, the overwhelming emotion was peace. He'd searched for this being for so long, to hear the words didn't sound fake, but confirming. He'd learned enough not to trust in God completely, but it was enough to know he hadn't been wrong about his creator's intentions, which seemed genuine.
"Whether or not the choice was mine, I would chose to be at your side," he responded simply, facing the other. Then he turned back to his drink. "I would fight to make the choice mine."
He still loved the world his father had created, and had never lost the love for the being, but he had tasted self reliance and independant thought, and treasured them. Experience taught him his will may not always be his own, and most of the time he longed for direction, but it was no longer a blind faith. His own values and priorities had developed, and though he didn't doubt Jesse could overpower him at will, or that other beings existed who could do the same. But if he'd learned anything from his time among the humans, it was the importance of fighting to keep control of oneself. And he'd learned that whatever he'd gone through, he cherished his father's creations more than anything. And how could he not still feel loyalty and love for the being that created it, not to mention himself?
"It would be an honor to be your friend. To stand at your side," he said finally, choosing his words carefully. "Though I believe I've been changed. I'm no longer what you created me to be."