Dragon's Curse: Elixir Quest (Volume 1)

Dragons relish the taste of fear.
Sir Joseph of Tredin thoroughly enjoys his job defending the border between human settlements and the dragon-lands by fighting and killing dragons. While his team keeps a tally for him, Joseph never indulges is such self-aggrandizement. Their effectiveness may be the reason why King Paol assigns the knight's team to the border more often than any other.
But when the King Paol falls mortally ill, an army from the mainland invades, and dragons demand sworn fealty from the king, Joseph must leave his wife yet again on a quest to seek a promised elixir to save the king's life. There are two minor obstacles: the elixir is hidden in the deadly dragon-lands, and to complete his quest, Joseph discovers he must become what he hates.