John Noble's Walter Bishop was unquestionably the heart of Fringe. He has all the traits of a mad scientist undercut with a terrible burden of guilt for his abduction of Peter, and Noble ensures that we can't help but sympathise with him. In Grey Matters, we discover that Walter's scattered behaviour is due to the removal of brain tissue, which the villain Thomas Jerome Newton restores to him in order to extract information. The transformation is extraordinary. Earlier in the episode, Walter seeks reassurance from Peter before he submits himself for an MRI scan, because he's scared of what he might find. The Walter who emerges with his brain intact is visibly colder and more calculating, and it's easy to imagine him as a far shadier figure in the show's mythology. The effect is chilling, especially since Newton is clearly a little unsettled himself. Of course, this Walter is a kind of prototype of Walternate, whose first appearance followed a few episodes later, but the sudden switch from the bumbling Walter we love to this sinister stranger is so masterfully captured by Noble that it's hard to resist Grey Matters.
