Fafnir

From The Elder Scrolls - Wiki on Neoseeker

Fafnir is a male Nord and is a member of the Dark Brotherhood. In the Whodunit? quest he acts as the doorman at Summitmist Manor. After the quest he disappears from the game.

Unique Dialogue

"So, the last guest finally arrives. I'll tell you what I told all the others. You go in. I lock the door. You don't come out 'til it's over. Now I'll tell you what I didn't tell everyone else. We have the same Mother, you and I. And she wants you to have this. It's the key to the house. I guess someone else has already told you the details. Kill all the guests then leave, right? Well, you'd better get in there. Time to mingle."