Lady grey may give you the solus greatsword but she is a murderer!!!
To prove this go to the grey house kill all the dead when they lock you in, at this point the grey cellar opens.
Go in.
you will find a desicated corpse of a young girl and a piece of parchment.
Read the parchment by (if your on the xbox and possibly something else) pressing select, then logbook, then books, the Scrawled Parchment, its the text that contains Lady Grey's older sister's
dying words. She talks about how she is the rightful heir to Bowerstone since
she is the oldest of the Grey Children. She also reveals that Elvira (lady grey) is the one
who locked her up in the cellar to die a slow death and that she renamed
herself Lady Grey.
Told you she was evil, but that's not stopping you from marrying a woman like
her is it?
