Stolen Destiny by Viola Grace

Kidnapped from the education station, Sil is set loose on a huge warship, only to find herself bound in a contract no one expected.

Silhouette watches the alien abductors trying to unload the entire shipment of stolen Terrans. She wished that she could sleep standing up, but it wasn’t a skill she had acquired.
When a medical team comes in, a grey alien comes by and tests the humans. When he gets to her and she goes off, there is relief in his expression. She is taken to medical, brought to stability, and they run some tests while stowing her in a cell for her own protection. The problem is there is a Hmrain in the next cell, and while his wings are gorgeous and look so soft, his eyes are so hot he could burn her.
Kalek is just finishing rut when this receptive human is dropped in next to him, but she needs calm, and he tries to give it, right up until the moment when his second in command makes an offhand remark about her prognosis and tries to remove her from his presence. Instinct takes over, and he breaks out of his cell.
Being chased by the captain of the ship is strange enough, but having him next to her when she wakes up from a painful medical procedure is shocking. He wants her body, mind, and soul, and maintaining her is part of the deal. He will hold up his end if she signs the contract to bind them together.