Even the Evil God is His servant.
The only consolation is that rescuing Katerina doesn't require facing the Lord of the Deep, who has ruled the world since the ancient Old Era, directly.
"He awakens with the stars returning to their place, still not having recovered his strength, sleeping deep under the sea. His followers and servants wander the coast, capturing and corrupting new servants..."
Katerina is most likely at a camp occupied by the Lord of the Deep's followers, servants, and believers.
And Andrea already has an answer regarding her whereabouts, although not so clearly.
Andrea, carrying an unconscious Katerina, sailed towards Vena Ice-Free Port, passing a certain bay. Some presences that made her uncomfortable quietly followed, but nothing happened until she reached the Ice-Free Port, they stopped following before getting close.
The City Hall took Katerina for treatment, while Andrea was enthusiastically taken to the shipyard for repairs.
