This takes place around Dawn since in Dawn Mosspelt is listed as a queen and Willowshine is her only kit. I figured Hawkfrost would fit even though she chose to remain in the nursery like Ferncloud.

Mosspelt sighed as she stared at her mate, Hawkfrost. Unknown to RiverClan, he was the father of her only daughter, Willowkit. Hawkfrost had told her never to admit this to anyone. Hawkfrost had never been clear with her on his feelings towards Mosspelt, but he had fathered her kits, so she liked to believe that he liked her, a least a little bit.

Moons later, Mosspelt would realize that Hawkfrost was evil and part of the Dark Forest uprising. She would never stop loving him and always kept it a secret.