Wings of the Night by Laura Taylor

The Gate of Chalandros is a mystical portal connecting the human world to the demon one. No one knows when or how it came into existence…
As a proud soldier of the salases, a black-skinned, horned species of warriors, Koradan has dedicated his life to serving the King of Chalandros. But heat, drought and famine are tearing his world apart, and so Koradan and a small company of his men are forced to cross the Gate of Chalandros into the human world. They mean to settle peacefully in the mountains, away from human civilisation, but when one of their dragon mounts is badly wounded, they are forced to make an emergency landing in a small, isolated village.
Lynette moved to the quiet mountainside village of Varismont ten years ago, after the death of her husband, to raise her only son in peace. But her tranquil life is shattered when a group of demons and their dragons land in the village in the dead of the night. Fearing for their lives, the villagers are forced to broker a deal with the demons – a deal in which Lynette, as the village’s only nurse, is expected to treat their wounded dragon and in doing so, get up close and personal with Koradan, the demons’ leader.
The longer Koradan and his men spend in the village, the more Lynette is forced to reconsider her views on the so-called ‘demons’ who are attempting to cross the mystical Gate. But Koradan wants far more than just a few medical supplies for the dragon. He speaks of negotiating peace between humans and demons – an idea that Lynette finds ludicrous. After all, everyone knows that demons are evil, and therefore not to be trusted…