V.M. Sang 
The Stones of Fire and Water [EPUB ebook] 

After his return from Aeris with the gem of air, Pettic receives a letter from the king. He is to see Torren and rekindle their relationship.
Soon after, Torren and Pettic meet a strange man and their lives change drastically, as they’re dragged into a mystery surrounding the red dragon Monarlisk and his former mate.
But will Pettic’s magic be enough to help them finish their quest in time – and in the end, will the rightful king be crowned?