Princess — Barbara Hambly

A novelette of 12,000 words, in the universe of Hambly's Dragonsbane (Winterlands) series. John Aversin, Dragonsbane and Thane of the Winterlands, and his partner the witch Jenny Waynest, are hired by a dragon to rescue a princess... who had originally made a deal with the dragon to carry her off and split her father's treasure. But the plan went amiss, and now the Princess needs rescuing from entities that the dragon doesn't want to tangle with.