You know the more I think about it I realize this door reminds me of an old creepy pasta story about a morrowind mod with a door that would open only on a certain day.
here is a link http://inuscreepystuff.blogspot.com/2010/09/jvk1166zesp.html
you can easily draw several parallels between the two.
1.)people out at night not knowing who they are saying the same things
2.)use a scroll of Icarian flight in morrowind at the top of the map you land near where the house is in dragonborn.
3.)It is a partial dwemer ruin.
4.)the shadow could relate to herma mora seems like his minions.
So my advice to everyone "watch the skys" ^.-
Haha, that was an interesting little read. The concept of something that would only open on a certain day is certainly an interesting one, but the rest of of was really lame.
NPCs eyes bleeding? Seriously? That's the biggest cliche in these stories-- plus it was pointless.
Plus the ending was a cop-out. It's like the guy didn't know how to end it.
Still, I'll feel a bit more uneasy whenever I go down there lol (the in-game notes about the house is creepy enough though)
=p
Edit: Oh, has anyone tried searching Hrodulf's body? Or the little boat he was near? Maybe there's something there.
If not, I think this is probably pointless that isn't meant to be anything.
=p