It wasn't that Castiel thought Joanna needed to be taken care of, the opposite was true, but he just didn't want her to be cold. She was a friend and he felt concerned for her well-being. It was a bit odd, to feel such concerned for someone who was not his charge or Sam, but it didn't both him as much as he thought it might. This was Jo, and he admired her. She was a good person and a worth ally, someone he was proud to fight alongside.
He considered what she was saying and was quiet for a long moment. The whiskey arrived and he took a sip, in equal parts because he really needed the drink and because it gave him a few more moments before he had to speak. Finally, he couldn't put it off any more. He didn't want to say more, for fear she would lose whatever respect she might have had for him. The thought of that made him feel strangely uncomfortable. Joanna was the one piece of home here, and he didn't want to lose that. And if her smile made him feel warm inside, well he didn't know enough to examine that closely.
"I am not only losing faith in my Father," he admitted. "If it were only that, it would not be so bad. My Father abandoned his creation...to not have doubts after such a thing would be truly blind. But I am also losing my faith in Dean, in our ability to stop Lucifer, and that worries me. I gave up everything for his sake, and if I cannot believe in him, does that mean that it was all for nothing? He didn't say yes to Michael...and that surprised me. It shouldn't have, because he is a good man and he would not just give up...but that I believed he would give in..." He trailed off and took another sip of whiskey.
"And I am losing faith in myself," he said finally. "My grace is fading, there is less of it than ever, and I do not know my place in this fight. I am not trying to disparage humanity. You are a noble race, very capable and deserving of respect. I just...do not know how not to be what I have been for so long. Without my grace, what use am I in the fight to come?"