Empire of the One (Wine of the Gods Book 12) by Pam Uphoff
Free for a couple of days - 12th book in the Wine of the Gods Series.
This is a spy story, I read it backwards for typos but I still enjoyed each read.
See also
http://madgeniusclub.com/2014/09/19/it-must-be-love/
They crossed the dimensions to spy on the World that attacked their own. The "Oners" had been very high tech, very aggressive, as magic as their own people. They went to collect information, and found a world preparing for war. Can they use this strange world's social conventions to derail that war?
http://www.amazon.com/gp/product/B00II99S58/
http://www.amazon.co.uk/gp/product/B00II99S58/
http://www.amazon.ca/gp/product/B00II99S58/