It's not the way Arthur words that that makes him immediately jump on that possibility -- it's that being in his presence is like being in a room full of broken clocks. He can sense his power, stronger now than it was the last time he was in a room with him, and it's his only guess. He said his original ability was similar to his and Peter's, after all, and he made a casual threat about having the opportunity to take his own abilities away from him, so he doesn't just borrow. Not like Peter.
no subject
It's not the way Arthur words that that makes him immediately jump on that possibility -- it's that being in his presence is like being in a room full of broken clocks. He can sense his power, stronger now than it was the last time he was in a room with him, and it's his only guess. He said his original ability was similar to his and Peter's, after all, and he made a casual threat about having the opportunity to take his own abilities away from him, so he doesn't just borrow. Not like Peter.