To Bind a Dark Heart by Kathryn Ann Kingsley

“Run, Gwen. Run as far and as hard as you can. Because when I catch you… You will belong to me.”
When she shattered the Iron Crystal and returned magic to Avalon, Gwen also shattered Mordred’s heart. Torn between her passion for Mordred and his rage at her betrayal, she fled into the wilds.
Gwen’s choice has transformed Avalon, and the island teems with magical wonders freed from the crystal. But Gwen also released the vicious and chaotic elementals. Desperate for revenge against Mordred, some of them see Gwen as an ally, others as a hostage.
Now, the Prince in Iron hunts Gwen relentlessly, though at night he visits her in dreams, unable to break the desire that binds them. She is his weakness. If his enemies captured her, he knows that he would make any deal, break any vow to return her to his side.
As the elementals prepare for battle, Gwen will face an impossible choice. Can she stand by as Avalon’s magic is destroyed once again? Or will she fight to overthrow the man she loves?