Forbidden Love - Merlyn 
Merlyn and Arthur Pendragon are two sides of the same coin. They're destinies entwined.
Merlyn had saved Arthur from vengeful mothers, cheating knights, watery plagues, poisonous drinks, frightening Griffins, murderous physicians, sacrificial Sidhe, revenge seeking wraiths, killer bandits and deadly Questing Beasts ... and that was only in her first year as his servant. Gods only know what she was to face next.
[Second book in Merlyn series]
[Second season of Merlin TV series]
(Merthur story - Arthur x female Merlin, following bbc tv series)
The front cover was created by @Uncharted247