The trembling of her body, it made him pull her in closer to him, not knowing why she was trembling, but still wanting to do what he could to fix it. She had no reason to be afraid or any other reason that would be why she was trembling and he was certain that it wasn't fear. Meg was someone he knew to be fearless, to be strong and that was something that was rare, even in a demon. Demons could sometimes be so quick to turn around and change with regimes and adjust their loyalty to someone so quickly. She was the only demon he could say that he actually cared about, because she had qualities that even an angel (although former, now) could admire. It was things that he didn't see in other demons that set her apart and made him think that she was one of the rare ones.
Castiel didn't move away from the softer touches, the insistence to be gentle, simply because Meg was now responding and touching him as well. That shiver traveled further up his spine when her hand moved up his back and another sound got caught, this time in his throat. He didn't just feel that arousal, the intimacy of this moment, but he felt something else. Something a little less tangible, but something with a name all the same. And it made him kiss her more firmly now, a bit more passionately, but not rough. Never rough. This was something he was committing to his memory, something he was truly experiencing for the first time and he wanted to note every detail, as best he could.
When his hand found the hem of her shirt, he hesitated, just for a moment, before his fingers moved against the bare skin that lay beneath it. He'd touched her bared arm earlier, when they were simply speaking and doing nothing more than that, but this was different. She was warm and smooth and it was something he realized, when he gazed upon her body that evening he caught her dancing in her home, he'd put thought to, but what he thought of did not match up to what it really felt like in the end.