Yeah I'm late to the finale but you don't understand how intensely I am focusing on the Manager and Arthur's dynamic right now.
My initial impression of the Manager was like, "Okay, cool, he's Kayne on Opposite Day." He wears a white suit instead of black, he chokes back his manic laughter, and he actively chooses to save people and give them comfort. Which, cool, I don't have any qualms about the guy, and sure, he's interesting, but I'm not falling over my chair to hear more about him.
But suddenly the finale hits and the Manager reveals so much more about himself. He is Kayne but with love. His love for his daughter fundamentally changed him, to the point that he now is on the opposite ethical fucking scale, in spite of the fact that he himself wanted to kill his father and become God of Everything, as long as he was with his daughter. Even after he loses his daughter, that love persists and shapes all of his future actions.
He repairs Kayne's damage. He repairs Arthur. He offers him a chance to enter a world where Faroe survives and Arthur can escape the horrors. He offers to wipe the slate clean. And when Arthur says no, and he chooses John, in spite of the fact that he desperately wants to be with Faroe, the Manager says nothing and gives all of it to him anyway.
He gives Arthur John and Faroe and Daniel and Arkham and his purpose and life again. He didn't have to do any of that. And sure, he gave it to him as a reward for all of Arthur's work, but why would he care? He's Nyarlathotep. Arthur is one tiny speck, bound to die in a sneeze of time, but the Manager does this for him.
And it just says so much about him. About his love and gentleness and care in spite of the fact that he doesn't have to be any of those things. And yes, the pull Kayne has towards Arthur is compelling---his constant obsession, this destructive sort of need to know every possible thing about Arthur---it's all so juicy. And you'd think the Manager doesn't have that, because he no longer has that power hunger, and thus not have that need to know quite literally everything, to the point that being unable to read a puny human would enrage him.
But maybe he does. Maybe it's a gentle sort of obsession---a need to make Arthur feel appreciated and cared for and swallowed by love. Maybe this Nyarlathotep is just as crazy for Arthur, but he needs him to smile, and he needs him happy.