“Once in a Lifetime” by Jill Shalvis. (Grand Central)

At the heart of every successful romance novel lies the evolution of its characters. Through love, heroes and heroines grow not only into a perfect match, but into stronger, better, more admirable people. Often, it is the hero who evolves most: Readers watch as the hard exterior of the classic alpha male is peeled away to reveal an emotional beta core (visible only to the heroine, of course). But what of the heroine and her evolution?

This month, three novels offer powerful looks at the way love can guide a heroine’s journey of self-discovery — and how feminine agency makes for great romance.

Aubrey Wellington has spent much of her life stirring up trouble in her small town, but after a particularly bad day that ends in her accidental attendance at an AA meeting, she decides to make amends. Jill Shalvis’s Once in a Lifetime (Grand Central; paperback, $6) follows Aubrey as she rights her wrongs, all while avoiding the worst one, which nearly ruined the life of Ben McDaniel, resident dreamboat. While Aubrey delays telling Ben the truth, the two fall for each other, making her ultimate confession even more dangerous. Sure enough, Ben can’t — or won’t — forgive her. The book is Aubrey’s journey, however, and she isn’t giving up. “Life is one big fat gamble,” she tells him, “The odds are never in your favor . . . but not playing? That’s the coward’s way out.” As Aubrey grows stronger and more certain, readers will cheer for her — and for the love she deserves.

Vampires and shape-shifters abound in Cynthia Eden’s Burn for Me (Brava/Kensington; paperback, $14), but the phoenix is the most powerful and invincible of her supernatural characters. Human-phoenix hybrid Cain is rescued from a torturous scientific experiment by intrepid reporter Eve Bradley. Soon, the two are on the run — after all, men planning to sell a perfect soldier to the government don’t take kindly to a meddling woman. Eve is more than a reporter with a heart of gold, however. She’s immune to the fire that consumes Cain each time he resurrects, which makes her both his greatest threat and his only link to sanity when he returns to his corporeal form (when the two burn in a different way). Eden takes the book to the next level by giving Eve a cloudy past with no understanding of who she is or why she can burn alongside a phoenix and survive. Only when Eve discovers the truth about herself can she harness her own power, give herself up to love and convince Cain that their love is worth any risk.

In Lorraine Heath’s When the Duke Was Wicked (Avon; paperback, $7.99), Lady Grace Mabry is intent on marrying for love (no easy task when one’s dowry is enormous), so she does what any self-respecting young woman in Victorian London would do: She finds herself a duke who can teach her how to tell the difference between fortune hunting and the real thing. Unfortunately, the duke in question is one she’s pined for since she was a child, and he’s such an expert in love because he’s had it — and lost it. Despite his vow never to love again, the widowed Duke of Lovingdon can’t help himself when it comes to Grace, and his lessons in spotting the emotion quickly spiral out of control (readers will never look at rum the same way after one scorching scene). But why is Grace so determined to marry for love? The answer is a powerful one, as medically plausible and emotionally damaging in Victorian London as it is in modern America. Scarred and scared, Grace makes a devastating choice for a lady in 1874: “I can’t make it work without falling in love. I won’t. I deserve a man who cares if I die.” Heath is known for her beautiful, deeply emotional romances, and this one is no different. “When the Duke Was Wicked” is a perfect read, full of tears and sighs and a heroine who is shocked by her own strength. Of course, readers won’t be surprised, and neither is Lovingdon. Which is precisely how it should be.

MacLean’s most recent historical romance is “No Good Duke Goes Unpunished.”