House Lothston
The ill-rumored bats of Harrenhal, holders of the cursed castle in this age — mad Lady Danelle rides out from it by night, the smallfolk whisper, and the whispers are getting worse.
The fuller tale
Harrenhal has never been a lucky seat to hold, and the Lothstons who rule it in this generation do nothing to break the pattern — bats on their banner, an ill reputation attached to the family for longer than anyone can precisely date, and a current lady, Danelle, whom the smallfolk whisper rides out from the castle by night on business no one cares to describe more specifically.
Whatever the truth of those whispers, Danelle Lothston plays a real, quiet part in the Whitewalls affair — assisting Brynden Rivers in the final days before the conspiracy collapses, helping close the net on Daemon II Blackfyre just before her own house's long decline finally catches up with it.
It is a fittingly grim footnote for a family holding a castle that has broken nearly everyone who has ever held it, going back to Harren the Black himself; the Lothstons' fall is simply the era's contribution to a pattern Harrenhal's later holders, generations on, would go on repeating under other names entirely.
The page and the screen
House Lothston and Harrenhal's role in the Whitewalls conspiracy belong to The Mystery Knight; neither has appeared in the aired season, whose action never reaches the riverlands' most cursed seat.