We created a decaying world, and fought to preserve it even as it crumbled. We had to be stopped.
~ Lucis Corin explains his motive to the Inquisitor and Cassandra Pentaghast.

Lucius Corin is the latest Lord Seeker, leader of the Seekers of the Truth in the videogame Dragon Age: Inquisition. He was promoted to this rank after death of Lord Seeker Lambert. He was known as a reasonable man but lost his sanity after he learned how the Seekers are created. He interpretated it as they are possessed by spirits and created a never-ending, non-stop war between Templars and mages. He decided that the world is decaying and cannot be saved, that it can be only destroyed to start everything from scratch. He joined the Order of Fiery Promise because they had exactly the same purpose and opposed the Seekers from the start. Instead of fighting Corypheus, also known as "The Elder One", he aided him in destroying the world. He allowed the Envy Demon to impersonate him and take over the Templar Order, when Lucius destroyed the Seekers by luring them to the Order of Fiery Promise, so they executed them. If the Inquisitor and Cassandra Pentaghast investiagate this in her personal quest "Promise of Destruction", they will find and kill him in battle after learning about all he did. If the Inquisitor sides with the Templars in the quest Champions of the Just, they will also discover that he attempted to corrupt them with the evil substance known as Red Lyrium. If Cassandra is in the Party, she will comment on believing that the Envy Demon impersonated him. If the Inquisitor sides with the mages in the quest In Hushed Whispers however, there will be no mention of him.