It's my thing, I suppose. (That's why I thought my Agent Carter story was really really obvious.)

re: Steve Trevor's backstory - other than being a spy who was undercover as a German pilot and there saw Ludendorff and Dr. Mora plotting, we don't hear anything, I think. (Mind you, they wisely avoided letting Chris Pine speak German. I strongly suspect the result otherwise would have entirely broken my suspension of disbelief with this whole undercover thing:)