Meredith is the only very few people who have not shown even a slight aggression towards Rood, and the way he just ket himself being hit and such, and the way he is just staring at only Rood.
Something tells me both Rood and his brother possessed human. His bro done it first, possessing the human and sacrificing his original body to help the human.
And rood dialogue in this chapter: "are you part of that everyone" and "you've suffered enough" and that meredith glow on the giant demon