Lord Kieran knew that despite being a human, Iris was a powerful magus he'd never encountered in his long life. From the moment he met her, he knew that her magic could be a great threat not only to her, but to those around her as well. He had also yet to find out why Iris wasn't affected by his shadows that could kill anyone and anything near him.
He initially thought that Iris would have a hard time surviving at Calaren Town when her magic burst during her encounters with the direwolves in the woods. He never thought that the human who dared to save his life would end up being sent as a tribute maiden by her own people and eventually forced to become his mate.
However, the more she used her magic, the more dangerous she became. Furthermore, the hint of darkness in her magic was growing at an alarming rate and Lord Kieran wasn't certain if Iris would be able to resist being corrupted by it.