"I don't know," Castiel replied promptly. "In my experience, the very few humans I know are...mercurial. They don't mean to be, but they are who they are. It's...awkward."
He didn't know why he mentioned it. Perhaps because he had no desire to be an irritation to his new friend or perhaps because he had no other friendships to reflect upon and make an accurate assessment. Though he supposed that if he mentioned it, it was a concern on some level and it was just as well to voice it. He would adapt accordingly. All he knew was that he liked Helena and hoped to continue interacting with her. Even if he often didn't know how.
As for her having a devil in her...that seemed cruel. And very strange. Humans often projected their own fears onto others and it was well-within their nature to, but to him, it seemed that by telling Helena there was a devil in her, that it would only serve to solidify such a mentality within her. "Demons are...they're pain incarnate," he explained. "Their souls are twisted. Even to the point where many no longer remember their human lives. And humans are nothing more than playthings in their eyes."
While it was true that Helena had done things that were almost on par with anything he'd seen demons do, he also knew that she had something they did not. She held remorse for her actions. Demons weren't even familiar with the concept. She was not one of them.
Nodding quietly, he watched idly as the cat he'd conjured wandered over to the tree and marked it with its claws. Below that, the fireworks waned on one side of the country only to grow more vibrant on the other. Some were likely the work of drunken barbecue attendees, but...they were happy. There were some lights he attributed to ambulance vehicles, but that was to be expected.
"Storybrooke is only one place," he agreed. "From here, you can actually see anything you want. In fact, if you would like, I could leave this place in your subconscious if you ever wish to revisit it."