Wow, thanks for such a detailed comment! Especially for saying Danny sounded in character - I find him so difficult to write without making him sound too much like a weepy teenage girl.

But I guess it's been a long time since that, and Danny's so
caught up in the crap that he can't remember being happy.

Yeah, exactly - he's not a happy boy, especially by the end of the series, and I'm not sure working in the lab would ever have been a relaxed kind of thing - that's ort of wishful thinking on his part, maybe.