Removing his hand from her, he watched her carefully for signs of fear or perhaps even anger. It was always difficult to discern. There were times where the Winchesters seemed angry with him, yet still wished for him to be present because his help was necessary. Castiel had just as easily assumed this was a human habit. Reading emotion was difficult, yet Cosima simply seemed confused. Or awed. That was better than angry.
"You're welcome," he said, tone as blunt as ever. "But to answer you question, I sought out the anomaly in your genetic makeup and corrected it. It...was a respiratory ailment, right? I found its origin. It's been eliminated completely. You're now as healthy as most other human females in your age group."
To him, it seemed as second nature as ever. He didn't see why it would be a "big" "deal," but then...perhaps there were no angels in her reality. Or at least, none that were visible or her or present on Earth. That seemed to be very common. "It is real," he said, nodding simply. "And yes. I am an angel of the Lord, though...this is not Heaven."
He hadn't meant to look into her thoughts. It was just that in close proximity, they were very loud. Also, when he healed people, he tended to catch...fragments. He wasn't going to mention it. "This is simply a place other than Earth. There is an Earth here, but there is no guarantee it will be the Earth as you know it. We all seem to be from very different places in time and space."