» Fri Aug 13, 2010 8:31 am Sometimes the Nightkin will not attack the Brahmin but only stand there cloaked unless he was recently attacked possibly by a Glowing One, if this happens, the Nightkin is in front of the house at night, or during the Day he is found behind a rock next to a broken fence, but if it is killed without seeing it as it is killing the Brahmin, the quest will be uncompletable. from http://fallout.wikia.com/wiki/Midnight_Ranch_Attacks
The Solution: I tried everything and finally solved it by using the old FO3 console command (TYPE:) "disable" and then reload a previous save and he will be invisible again until about 12AM he will starting shooting the brahmins and you can kill him now and gain the dialogue option from Dusty MrBride.
EDIT: Can somebody please edit the title for me from "Quest" into "Unmarked Quest"? Thanks
