Dear anon, thank you for the many compliments.
(I must be completely heartless, because I have never had the faintest sympathy for Dan in all of the situations I put him into, and everyone else does! Amy, on the other hand…)
Regarding Amy and purple… I would have to go back and review, but I am reasonably sure that she only wears purple in season 3. Actually…wait, I’m wrong, she wears a dark purple dress in the very first episode (which Dan’s tie matches) at the drinks event.
When Amy’s feeling confident she tends to dress in a particular spectrum of colours – green to blue to purple – which I think is partly to distinguish her from Selina, red being Selina’s colour of confidence. The other reason, of course, being that Anna Chlumsky looks smashing in those colours (green in particular – I always want to tell her stylist or whoever it is to get her green for the red carpet). When she’s depressed, or feeling under threat, she retreats to black-brown-navy.
Which, again, speaks to how threatening Amy found Dan in early season one – in the first episode she wears pink and purple and blue, but changes to wearing suits and only suits very shortly after he starts working with her. It’s an attempt (almost certainly subconscious) to kind of de-sexualise herself in his eyes, so he will, for instance, stop bringing up the fact that they’ve dated, and ideally, stop flirting with her. (It doesn’t work, of course, because Dan’s attraction to Amy isn’t something she can really control, but that is the aim).
That said, the use of purple specifically, didn’t jump out at me at all – it’s fairly easy to track what Amy in red or pink or nude means, because those colours are used very deliberately… and Dan and Amy in green and blue has been reused enough times that it’s easy to work out what it’s supposed to tell us about them. Of course, I’m not an expert on the subject… far from it, so if anyone has any suggestions, please share.