User blog comment:Zippertrain85/The reasons why Serana is not from the First Era./@comment-121.219.169.69-20130518094845/@comment-124.181.209.130-20130520074423

Regarding the colour is reading to much into it I believe. I doubt the devs paid mind to that.

As for the Vilgalmo thing, I wouldn't know. Haven't played Dawnguard though I do know a fair amount about it (story, whatnot).