Return of the Changeling (The Changeling Saga: Book Three) by Ian P Buckingham
The family's connection was so deep it undermned the Werewytch's reign.
So, banished and brainwashed they spent cold decades apart, a lifetime in the dark.
Then, at the thinning of the veil between the world of the Fae and mankind, fate set them on a course for unification. It also became a date with an evil destiny far more powerful than they could imagine.
This is the third book in The Changeling Saga, a story of magick and mystery. The series follows an enchanted Cornish dynasty as they uncover enemies, challenges, powers, artefacts and allies in a war against a toxic pandemic that transcends countries, continents and worlds.