Lady Mary--Pride & Prejudice by Jane Austen
Mary should have no problem connecting to the story of sisters who need to marry or find themselves penniless and homeless. She could also stand to think a bit about being too proud.
Mr. Bates--Psycho by Robert Bloch
If nothing else he'll finally figure out why The Bates Motel is a really bad idea.
Thomas--The Prince by Machiavelli
He's going to need all the help he can get if he keeps up the feud he has going with O'Brien.
Edith--Miss Pettigrew Lives for a Day by Winifred Watson
Hopefully Edith would find this ugly duckling story inspiring--as long as she doesn't take it too far (she totally would). Alternate read would be Stranger In My Arms by Lisa Kleypas if that Canadian "Patrick" guy comes back.
Carson--The House of Mirth by Edith Wharton
You know Carson's really a romantic at heart, but his sense of social hierarchy and propriety probably makes him a bit of pessimist. Enter Edith Wharton!
What books would you recommend for Downton characters?