User blog comment:Zippertrain85/The reasons why Serana is not from the First Era./@comment-9156240-20130508234036/@comment-26474238-20130509205558

It's relevant because you're acting like that castle is tied in with when Harkon and his family first came into existence, when there's no such thing saying that's the case. There's no telling when that castle was built, who it was built by, when Harkon took it over, and whether it actually has any relevance to Harkon and his kin aside from being their current home in Skyrim.