Wheel of Time

Season 2 was a significant upgrade from S1.

Evil Ruins is Shadar Logoth, a once good and prosperous city that slowly became selfish and paranoid. The effect became so powerful that the city itself became infected with an evil taint that lingers on every stone and item in the confines of the city.

The Children of the Light are an Inquisition analog. Any group that uses violence, black/white thinking and believing that any actions they perform MUST be good, because they are performing it and they are good is prime real-estate for infection by Darkfriends.

In the books, the red ruby dagger is a conduit for that evil, which is distinct from the Dark One's evil.
Padin Fain was a Darkfriend who became obsessed with the dagger, merged with it's evil and became something new entirely. He acts as a 3rd side in the Dragon vs Dark One struggle.
Making him one of the Chosen neatens the story up a little, but I think we'll miss the chaos of his presence.