An interesting question.
There are many characteristics I could come up with, some of which you might agree with, some you might not.
The article “What Traits Make a Good Romance Heroine,” by Roz Denny Fox, hits the nail on the head with the statement, “A romance heroine needs to be someone any other woman would like to be.” That is the cardinal rule—you need a sympathetic heroine. I had one reader tell me she really wanted best friends of one of my heroines. That may have been the best compliments I’ve had on that book.
In “Three Characteristics a Heroine Should and Should Not Have,” Jeffe Kennedy states that the most important characteristics a heroine should have are to be believable, be relatable, and be admirable. However, it is my belief that in order to keep heroines of historical romances relatable and admirable, authors in that genre have to sometimes sacrifice believability. Our historical heroines have to reflect the changing times and our changing sensibilities about women.
To be believable, relatable, and admirable today, heroines in historicals must have a bit more spunk that would usually be found in women of the period. Because of the feminist movement of the 1970s that convinced women they were just as capable as men in every arena, women today have grown up with that sensibility.
Readers today want to see a resilient heroine who can meet every challenge without waiting for a man to rescue her. In fact, many heroines not only save themselves, but their heroes as well. My favorite instance of this occurs in Jo Beverley’s Devilish, when the heroine out-shoots the hero and saves his life. These heroines are sympathetic and very entertaining, but are they a reflection of today’s woman or the woman of the period?
Remember, our heroine has to be believable. How many women throughout history knew how to fight with sword and pistol? Could drive a carriage? Was adept at piloting her own ship? Was head of a spy ring? There may have been some, but I suspect they were a small minority throughout history.
Historical romance authors especially walk a fine line today with regards to their heroines. They have to find ways to make these women appeal to contemporary audiences, while still holding true to the period. One way to do this is to research your time period thoroughly. Find stories of true heroines and incorporate their characteristics with your heroine’s to make a composite woman who is true to herself and her niche in time.