Daughter of Time by Sarah Woodbury

Sometimes, finally facing what you most fear turns out to be no more difficult than putting one foot in front of the other … A medieval man with an uncertain destiny, Llywelyn, the Prince of Wales, faces treachery and deceit at the hands of friends and foes alike. When Meg slips through time into medieval Wales, the pair must navigate the shifting allegiances that threaten the very existence of Wales–and create their own history that defies the laws of time. Open the door to an alternate world of princes and castles in the prequel to the After Cilmeri series! Complete series reading order: Daughter of Time, Footsteps in Time, Winds of Time, Prince of Time, Crossroads in Time, Children of Time, Exiles in Time, Castaways in Time, Ashes of Time, Warden of Time, Guardians of Time, Masters of Time, Outpost in Time, Shades of Time, Champions of Time, Refuge in Time, Unbroken in Time, Outcasts in Time, Hidden in Time, Legacy of Time. Also, This Small Corner of Time: The After Cilmeri Series Companion.