House of the Star by Caitlin Brennan

Elen is the Princess of Ymbria, a world who has lately been at war with the world of Caledon. Because neither side will give up fighting between the two worlds, the Worldriders have decreed a peace to be made: Both sides will send one of their own to Earth, to the ranch where the worldrunner horses live and breed, and there, they will serve together to keep peace not only between Ymbria and Caledon, but between all the worlds, and Earth as well.

Elen is more than happy to be a worldrider, but make peace with a Caledonian? Never! She hopes that she can use her powers to open doors between worlds simply to ride and keep riding her horse, Blanca, and avoid the future that has been decided for her, but it is not to be. Blanca will only take her to Earth, and once there, will prevent her from going to any other world until she enters the House of the Star and becomes an actual worldrider.

Elen's main problem is with the Caledonian rider, a girl known as Ria. When she becomes aware that Ria is from Caledon, she is convinced that the other girl is a liar, and once she is forced to make peace with her, she decides that she has to keep an eye on her, to prevent the treachery that she knows will come from Caledon. But will Caledon bring treachery? Or will that come from Ymbria? For Elen has been lied to by her own people, and both sides want to steal the worldrider horses for their own, and escape the punishing confinement that has been laid on their worlds by the worldriders.

But as Ria and Elen learn to work together to keep the beautiful worldrider horses safe and why the horses can only breed on Earth, something happens that can set their worlds at odds once more, and both must learn to trust and find out the truth to discover who is really at fault in the war, and who can be trusted. Can the two girls work together for the gain of both their worlds, or will they be forced apart and to return to their peoples forever if they can't somehow make peace between themselves and their own families?

I first read Caitlin Brennan's fantasy romances for Luna books, and just like that series, House of the Star involves white horses with otherworldly powers, making it just perfect for younger, horse-mad girls. Elen is just at that age when a horse can be not only a pet, but a friend and companion, too, and she bonds with Ria over the horses, as both girls love the horses, even if they hate or don't like each other.

But it is when the horses are threatened with stealing and extinction that each girl learns to trust each other. Both know that their worlds will suffer if they are not allowed to trade with others, because each lacks something that they need to live, and of course, each world needs what the other one has. But it is the knowledge that both worlds are at fault that allows the girls to make peace with each other, and to have their worlds make peace.

The story is told from Elen's point of view, and by the end of the story, she has found out things about her family and her world that make her look at them quite differently from the "only my world is right and sinned against" attitude she had at the beginning. I found myself really enjoying the story, and at least some adults in this tale were trustworthy, and in the end, Elen manages to make peace and find friends. I am hoping this story is just the first in a series of stories based around the worldriders and the various worlds, as I would love reading more about everything. Well done, and makes me want to read more... a lot more. Highly recommended.