Possible Clues:

• The Strange Case of Dr . . . . . . and Mr Hyde
• He became Hyde
• Hyde was his alter ego
• See 1 Across
• One of two title characters in a book with one title character
• Doctor who creates a dangerous serum
• Side Hyde tried to hide
• Stevenson title doctor
• Henry __, Edward Hyde's better half?
• Gertrude --, English horticulturist and garden designer